CWE-79
AllowedImproper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
Abstraction: Base · Status: Stable
The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users.
70038 vulnerabilities reference this CWE, most recent first.
GHSA-C2MQ-Q2FV-FFHW
Vulnerability from github – Published: 2025-01-24 12:31 – Updated: 2026-04-01 18:33Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') vulnerability in NotFound One Backend Language allows Reflected XSS. This issue affects One Backend Language: from n/a through 1.0.
{
"affected": [],
"aliases": [
"CVE-2025-23837"
],
"database_specific": {
"cwe_ids": [
"CWE-79"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2025-01-24T11:15:11Z",
"severity": "HIGH"
},
"details": "Improper Neutralization of Input During Web Page Generation (\u0027Cross-site Scripting\u0027) vulnerability in NotFound One Backend Language allows Reflected XSS. This issue affects One Backend Language: from n/a through 1.0.",
"id": "GHSA-c2mq-q2fv-ffhw",
"modified": "2026-04-01T18:33:23Z",
"published": "2025-01-24T12:31:09Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2025-23837"
},
{
"type": "WEB",
"url": "https://patchstack.com/database/wordpress/plugin/one-backend-language/vulnerability/wordpress-one-backend-language-plugin-1-0-reflected-cross-site-scripting-xss-vulnerability?_s_id=cve"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:L",
"type": "CVSS_V3"
}
]
}
GHSA-C2MW-Q3H6-PVX6
Vulnerability from github – Published: 2024-06-27 18:31 – Updated: 2024-06-27 18:31IBM WebSphere Application Server 8.5 and 9.0 is vulnerable to cross-site scripting. This vulnerability allows a privileged user to embed arbitrary JavaScript code in the Web UI thus altering the intended functionality potentially leading to credentials disclosure within a trusted session. IBM X-Force ID: 292640.
{
"affected": [],
"aliases": [
"CVE-2024-35153"
],
"database_specific": {
"cwe_ids": [
"CWE-79"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2024-06-27T18:15:18Z",
"severity": "MODERATE"
},
"details": "IBM WebSphere Application Server 8.5 and 9.0 is vulnerable to cross-site scripting. This vulnerability allows a privileged user to embed arbitrary JavaScript code in the Web UI thus altering the intended functionality potentially leading to credentials disclosure within a trusted session. IBM X-Force ID: 292640.",
"id": "GHSA-c2mw-q3h6-pvx6",
"modified": "2024-06-27T18:31:32Z",
"published": "2024-06-27T18:31:32Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2024-35153"
},
{
"type": "WEB",
"url": "https://exchange.xforce.ibmcloud.com/vulnerabilities/292640"
},
{
"type": "WEB",
"url": "https://www.ibm.com/support/pages/node/7158662"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:C/C:L/I:L/A:N",
"type": "CVSS_V3"
}
]
}
GHSA-C2P4-PCJ7-R7GW
Vulnerability from github – Published: 2022-05-17 03:01 – Updated: 2022-05-17 03:01IBM Kenexa LMS on Cloud 13.1 and 13.2 - 13.2.4 is vulnerable to cross-site scripting. This vulnerability allows users to embed arbitrary JavaScript code in the Web UI thus altering the intended functionality potentially leading to credentials disclosure within a trusted session.
{
"affected": [],
"aliases": [
"CVE-2016-8920"
],
"database_specific": {
"cwe_ids": [
"CWE-79"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2017-02-01T20:59:00Z",
"severity": "MODERATE"
},
"details": "IBM Kenexa LMS on Cloud 13.1 and 13.2 - 13.2.4 is vulnerable to cross-site scripting. This vulnerability allows users to embed arbitrary JavaScript code in the Web UI thus altering the intended functionality potentially leading to credentials disclosure within a trusted session.",
"id": "GHSA-c2p4-pcj7-r7gw",
"modified": "2022-05-17T03:01:52Z",
"published": "2022-05-17T03:01:52Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2016-8920"
},
{
"type": "WEB",
"url": "http://www.ibm.com/support/docview.wss?uid=swg21993982"
},
{
"type": "WEB",
"url": "http://www.securityfocus.com/bid/94303"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.0/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N",
"type": "CVSS_V3"
}
]
}
GHSA-C2P4-PF84-GVQV
Vulnerability from github – Published: 2022-04-29 03:01 – Updated: 2022-04-29 03:01Cross-site scripting (XSS) vulnerability in register.asp in Snitz Forums 2000 3.4.04 and earlier allows remote attackers to inject arbitrary web script or HTML via javascript events in the Email parameter.
{
"affected": [],
"aliases": [
"CVE-2004-2720"
],
"database_specific": {
"cwe_ids": [
"CWE-79"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2004-12-31T05:00:00Z",
"severity": "MODERATE"
},
"details": "Cross-site scripting (XSS) vulnerability in register.asp in Snitz Forums 2000 3.4.04 and earlier allows remote attackers to inject arbitrary web script or HTML via javascript events in the Email parameter.",
"id": "GHSA-c2p4-pf84-gvqv",
"modified": "2022-04-29T03:01:59Z",
"published": "2022-04-29T03:01:59Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2004-2720"
},
{
"type": "WEB",
"url": "https://exchange.xforce.ibmcloud.com/vulnerabilities/16444"
},
{
"type": "WEB",
"url": "http://forum.snitz.com/forum/topic.asp?TOPIC_ID=53360"
},
{
"type": "WEB",
"url": "http://secunia.com/advisories/11895"
},
{
"type": "WEB",
"url": "http://securityreason.com/securityalert/3200"
},
{
"type": "WEB",
"url": "http://securitytracker.com/id?1010524"
},
{
"type": "WEB",
"url": "http://www.osvdb.org/7190"
},
{
"type": "WEB",
"url": "http://www.sec-tec.co.uk/vulnerability/snitzxss.html"
},
{
"type": "WEB",
"url": "http://www.securityfocus.com/archive/1/366309"
},
{
"type": "WEB",
"url": "http://www.securityfocus.com/bid/10564"
}
],
"schema_version": "1.4.0",
"severity": []
}
GHSA-C2P9-97WW-Q2Q5
Vulnerability from github – Published: 2025-02-11 12:30 – Updated: 2025-02-11 12:30The GeoDirectory – WP Business Directory Plugin and Classified Listings Directory plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the display_name profile parameter in all versions up to, and including, 2.8.97 due to insufficient input sanitization and output escaping. This makes it possible for authenticated attackers, with Subscriber-level access and above, to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page.
{
"affected": [],
"aliases": [
"CVE-2024-13506"
],
"database_specific": {
"cwe_ids": [
"CWE-79"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2025-02-11T11:15:12Z",
"severity": "MODERATE"
},
"details": "The GeoDirectory \u2013 WP Business Directory Plugin and Classified Listings Directory plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the display_name profile parameter in all versions up to, and including, 2.8.97 due to insufficient input sanitization and output escaping. This makes it possible for authenticated attackers, with Subscriber-level access and above, to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page.",
"id": "GHSA-c2p9-97ww-q2q5",
"modified": "2025-02-11T12:30:54Z",
"published": "2025-02-11T12:30:54Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2024-13506"
},
{
"type": "WEB",
"url": "https://plugins.trac.wordpress.org/browser/geodirectory/tags/2.8.97/includes/admin/class-geodir-admin-post-view.php#L317"
},
{
"type": "WEB",
"url": "https://plugins.trac.wordpress.org/changeset/3225839"
},
{
"type": "WEB",
"url": "https://www.wordfence.com/threat-intel/vulnerabilities/id/d0d9ba14-c0c9-426e-927e-9139a0882f0d?source=cve"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N",
"type": "CVSS_V3"
}
]
}
GHSA-C2PC-G3HH-8RHM
Vulnerability from github – Published: 2024-04-24 21:31 – Updated: 2024-04-24 21:31A vulnerability in the web-based management interface of Cisco TelePresence Management Suite (TMS) Software could allow an authenticated, remote attacker to conduct a cross-site scripting (XSS) attack against a user of the interface. This vulnerability is due to insufficient input validation by the web-based management interface. An attacker could exploit this vulnerability by inserting malicious data in a specific data field in the interface. A successful exploit could allow the attacker to execute arbitrary script code in the context of the affected interface or access sensitive, browser-based information.
{
"affected": [],
"aliases": [
"CVE-2023-20249"
],
"database_specific": {
"cwe_ids": [
"CWE-79"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2024-04-24T21:15:46Z",
"severity": "MODERATE"
},
"details": "A vulnerability in the web-based management interface of Cisco TelePresence Management Suite (TMS) Software could allow an authenticated, remote attacker to conduct a cross-site scripting (XSS) attack against a user of the interface. This vulnerability is due to insufficient input validation by the web-based management interface. An attacker could exploit this vulnerability by inserting malicious data in a specific data field in the interface. A successful exploit could allow the attacker to execute arbitrary script code in the context of the affected interface or access sensitive, browser-based information.",
"id": "GHSA-c2pc-g3hh-8rhm",
"modified": "2024-04-24T21:31:58Z",
"published": "2024-04-24T21:31:58Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2023-20249"
},
{
"type": "WEB",
"url": "https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-tms-portal-xss-AXNeVg3s"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N",
"type": "CVSS_V3"
}
]
}
GHSA-C2PM-JWHM-8XMF
Vulnerability from github – Published: 2025-04-01 06:30 – Updated: 2026-04-01 18:34Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') vulnerability in Cristiano Zanca WooCommerce Fattureincloud allows Reflected XSS. This issue affects WooCommerce Fattureincloud: from n/a through 2.6.7.
{
"affected": [],
"aliases": [
"CVE-2025-30837"
],
"database_specific": {
"cwe_ids": [
"CWE-79"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2025-04-01T06:15:52Z",
"severity": "HIGH"
},
"details": "Improper Neutralization of Input During Web Page Generation (\u0027Cross-site Scripting\u0027) vulnerability in Cristiano Zanca WooCommerce Fattureincloud allows Reflected XSS. This issue affects WooCommerce Fattureincloud: from n/a through 2.6.7.",
"id": "GHSA-c2pm-jwhm-8xmf",
"modified": "2026-04-01T18:34:17Z",
"published": "2025-04-01T06:30:46Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2025-30837"
},
{
"type": "WEB",
"url": "https://patchstack.com/database/wordpress/plugin/woo-fattureincloud/vulnerability/wordpress-woocommerce-fattureincloud-plugin-2-6-7-cross-site-scripting-xss-vulnerability?_s_id=cve"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:L",
"type": "CVSS_V3"
}
]
}
GHSA-C2PV-MPV5-96HP
Vulnerability from github – Published: 2022-05-17 03:00 – Updated: 2022-05-17 03:00IBM Connections is vulnerable to cross-site scripting, caused by improper validation of user-supplied input. A remote attacker could exploit this vulnerability using a specially-crafted URL to execute script in a victim's Web browser within the security context of the hosting Web site, once the URL is clicked. An attacker could use this vulnerability to steal the victim's cookie-based authentication credentials.
{
"affected": [],
"aliases": [
"CVE-2016-0305"
],
"database_specific": {
"cwe_ids": [
"CWE-79"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2017-02-08T22:59:00Z",
"severity": "MODERATE"
},
"details": "IBM Connections is vulnerable to cross-site scripting, caused by improper validation of user-supplied input. A remote attacker could exploit this vulnerability using a specially-crafted URL to execute script in a victim\u0027s Web browser within the security context of the hosting Web site, once the URL is clicked. An attacker could use this vulnerability to steal the victim\u0027s cookie-based authentication credentials.",
"id": "GHSA-c2pv-mpv5-96hp",
"modified": "2022-05-17T03:00:53Z",
"published": "2022-05-17T03:00:53Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2016-0305"
},
{
"type": "WEB",
"url": "http://www.ibm.com/support/docview.wss?uid=swg21986770"
},
{
"type": "WEB",
"url": "http://www.securityfocus.com/bid/92436"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.0/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N",
"type": "CVSS_V3"
}
]
}
GHSA-C2PX-C8X4-V6MQ
Vulnerability from github – Published: 2023-07-06 19:24 – Updated: 2024-04-04 05:37Auth. (contributor+) Cross-Site Scripting (XSS) vulnerability in Google Maps v3 Shortcode plugin <= 1.2.1 versions.
{
"affected": [],
"aliases": [
"CVE-2023-23827"
],
"database_specific": {
"cwe_ids": [
"CWE-79"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2023-04-23T11:15:07Z",
"severity": "MODERATE"
},
"details": "Auth. (contributor+) Cross-Site Scripting (XSS) vulnerability in Google Maps v3 Shortcode plugin \u003c=\u00a01.2.1 versions.",
"id": "GHSA-c2px-c8x4-v6mq",
"modified": "2024-04-04T05:37:36Z",
"published": "2023-07-06T19:24:17Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2023-23827"
},
{
"type": "WEB",
"url": "https://patchstack.com/database/vulnerability/google-maps-v3-shortcode/wordpress-google-maps-v3-shortcode-plugin-1-2-1-cross-site-scripting-xss-vulnerability?_s_id=cve"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:L",
"type": "CVSS_V3"
}
]
}
GHSA-C2Q3-P4JR-C55F
Vulnerability from github – Published: 2026-05-05 21:24 – Updated: 2026-05-13 14:04Summary
A Stored Cross-Site Scripting (XSS) vulnerability exists in the Grav CMS Form plugin's select field template. Taxonomy tag and category values are rendered with the Twig |raw filter in the admin panel, bypassing the global autoescape protection. An editor-level user can inject arbitrary JavaScript that executes in any administrator's browser session when they view or edit any page in the admin panel.
Additionally, Grav's built-in XSS detection (Security::detectXss()) can be bypassed by using payloads that close the <option>/<select> context and use unquoted event handlers - the on_events regex fails to match event handlers without quotes or trailing spaces before >.
Important
- The vulnerability is in the Form plugin (
select.html.twig), which is installed by default with Grav - The XSS is cross-page: a malicious taxonomy value on one page executes when an admin edits any page, because taxonomy options are rendered from a shared global pool
- An editor can exploit this without any other vulnerability - taxonomy fields are not in the server-side restricted fields list
- The
HttpOnlyflag on session cookies prevents direct session theft, but the XSS can steal the admin nonce and perform privileged actions via JavaScript
Permissions Needed
- Editor: can create or edit pages and set taxonomy tag/category values
Details
The Form plugin's select field template renders option values using the |raw Twig filter, which outputs content without HTML escaping:
File: user/plugins/form/templates/forms/fields/select/select.html.twig
{# Line 55 #}
avalue|raw
{# Line 65 #}
suboption|t|raw
{# Line 72 #}
item_value|t|raw
The taxonomy field in the page editor uses this select template. When a page has taxonomy values (tags, categories), these values are populated as <option> elements in the select dropdown. The value attribute is properly escaped by the browser's attribute encoding, but the display text between <option> tags is rendered raw:
<option value="<script>alert(1)</script>"><script>alert(1)</script></option>
Since taxonomy options are collected globally across all pages (to provide autocomplete/selection), a malicious taxonomy value on any page will appear in the taxonomy dropdown of every page editor - making this a cross-page stored XSS.
The server-side field restriction in the flex-objects plugin only blocks ['form', 'forms', 'process', 'twig'] for non-super users. Taxonomy fields are not restricted, so editors can freely set arbitrary taxonomy values.
XSS Detection Bypass
Grav's Security::detectXss() checks for dangerous_tags (e.g., <script>, <iframe>), on_events (event handlers), and invalid_protocols (e.g., javascript:). However, the on_events regex:
'on_events' => '#(<[^>]+[a-z\x00-\x20"\'\/)(?:on[a-z]+)\s*=[\s|\'"'].*[\s|\'"']>#iUu'
requires either quotes around the handler value or a trailing space before >. An unquoted handler like onerror=alert(1)> (no space before >) bypasses this check entirely.
Combined with </option></select> to break out of the select context (neither tag is in dangerous_tags), the full payload evades all three detection layers and triggers no XSS warning in the admin panel.
PoC
Step 1: Login as Editor
Navigate to http://TARGET/admin/ and authenticate with editor credentials.
Step 2: Create a Page with Malicious Taxonomy
- Go to Pages → Add → Add Page
- Title:
XSS via editor - Go to Options Tap
- On Taxonomies, Add tag:
</option></select><img src=x onerror=alert('XSS-via-editor')>
This payload:
- Closes </option></select> to break out of the select dropdown context
- Injects an <img> tag with an unquoted onerror handler (bypasses on_events regex)
- Is not in the dangerous_tags list (no <script>, <iframe>, etc.)
- Triggers no XSS warning in the admin panel
Step 3: Trigger the XSS
When any administrator navigates to the page editor of any page (not just the malicious one), the JavaScript executes immediately.
The XSS fires because taxonomy tag options are collected globally across all pages and rendered with |raw in the select dropdown template. The payload breaks out of the <option> context, and the browser renders the <img> tag as a regular DOM element.
Impact
- Session hijacking: While
HttpOnlyprevents direct cookie theft, the XSS can steal the admin nonce token and perform any admin action via AJAX requests - Privilege escalation: An editor can perform admin-only actions (create users, modify system configuration, install plugins) through the hijacked admin session
- Cross-page impact: A single malicious taxonomy value affects the entire admin panel - every page editor view is compromised
Maintainer note — fix applied (2026-04-24)
Fixed across two repos:
-
grav-plugin-form 9.0.1 (commit
6bffb4c) — the primary fix. All four|rawfilters intemplates/forms/fields/select/select.html.twig(placeholder, avalue, suboption, item_value) have been removed. Option labels — including taxonomy values that propagate cross-page through the admin's shared selection pool — now go through Twig's default escaper, so a lower-privileged editor can no longer inject script that runs in an admin's browser when they open any page editor. -
Grav core on the
2.0branch (commit5a12f9be8, ships in 2.0.0-beta.2) — closes the detection-bypass half of the report. Theon_eventsregex inSecurity::detectXss()is tightened so unquoted handlers likeonerror=alert(1)>are flagged (see separate GHSA-9695-8fr9-hw5q), andoption/selecthave been added to defaultsecurity.xss_dangerous_tagsso</option></select>…tripwires the detector (see separate GHSA-w8cg-7jcj-4vv2).
Sites running admin2 on Grav 2.0.0-beta.2 get the 9.0.1 form plugin automatically via its existing dependency graph.
Files:
- templates/forms/fields/select/select.html.twig — four |raw removed.
- system/config/security.yaml — dangerous-tags list extended.
- system/src/Grav/Common/Security.php — on_events regex tightened.
- tests/unit/Grav/Common/Security/DetectXssTest.php — includes the GHSA-c2q3 PoC payload.
{
"affected": [
{
"package": {
"ecosystem": "Packagist",
"name": "getgrav/grav"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "2.0.0-beta.2"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [
"CVE-2026-42842"
],
"database_specific": {
"cwe_ids": [
"CWE-79"
],
"github_reviewed": true,
"github_reviewed_at": "2026-05-05T21:24:45Z",
"nvd_published_at": "2026-05-11T17:16:33Z",
"severity": "MODERATE"
},
"details": "### Summary\n\nA Stored Cross-Site Scripting (XSS) vulnerability exists in the Grav CMS Form plugin\u0027s select field template. Taxonomy tag and category values are rendered with the Twig `|raw` filter in the admin panel, bypassing the global autoescape protection. An editor-level user can inject arbitrary JavaScript that executes in any administrator\u0027s browser session when they view or edit any page in the admin panel.\n\nAdditionally, Grav\u0027s built-in XSS detection (`Security::detectXss()`) can be bypassed by using payloads that close the `\u003coption\u003e/\u003cselect\u003e` context and use unquoted event handlers - the `on_events` regex fails to match event handlers without quotes or trailing spaces before `\u003e`.\n\n### Important\n\n- The vulnerability is in the Form plugin (`select.html.twig`), which is installed by default with Grav\n- The XSS is cross-page: a malicious taxonomy value on one page executes when an admin edits any page, because taxonomy options are rendered from a shared global pool\n- An editor can exploit this without any other vulnerability - taxonomy fields are not in the server-side restricted fields list\n- The `HttpOnly` flag on session cookies prevents direct session theft, but the XSS can steal the admin nonce and perform privileged actions via JavaScript\n\n### Permissions Needed\n\n- Editor: can create or edit pages and set taxonomy tag/category values\n\n### Details\n\nThe Form plugin\u0027s select field template renders option values using the `|raw` Twig filter, which outputs content without HTML escaping:\n\nFile: `user/plugins/form/templates/forms/fields/select/select.html.twig`\n\n```twig\n{# Line 55 #}\n avalue|raw \n\n{# Line 65 #}\n suboption|t|raw \n\n{# Line 72 #}\n item_value|t|raw \n```\n\nThe taxonomy field in the page editor uses this select template. When a page has taxonomy values (tags, categories), these values are populated as `\u003coption\u003e` elements in the select dropdown. The `value` attribute is properly escaped by the browser\u0027s attribute encoding, but the **display text** between `\u003coption\u003e` tags is rendered raw:\n\n```html\n\u003coption value=\"\u0026lt;script\u0026gt;alert(1)\u0026lt;/script\u0026gt;\"\u003e\u003cscript\u003ealert(1)\u003c/script\u003e\u003c/option\u003e\n```\n\nSince taxonomy options are collected globally across all pages (to provide autocomplete/selection), a malicious taxonomy value on any page will appear in the taxonomy dropdown of every page editor - making this a cross-page stored XSS.\n\nThe server-side field restriction in the flex-objects plugin only blocks `[\u0027form\u0027, \u0027forms\u0027, \u0027process\u0027, \u0027twig\u0027]` for non-super users. Taxonomy fields are not restricted, so editors can freely set arbitrary taxonomy values.\n\n### XSS Detection Bypass\n\nGrav\u0027s `Security::detectXss()` checks for `dangerous_tags` (e.g., `\u003cscript\u003e`, `\u003ciframe\u003e`), `on_events` (event handlers), and `invalid_protocols` (e.g., `javascript:`). However, the `on_events` regex:\n\n```php\n\u0027on_events\u0027 =\u003e \u0027#(\u003c[^\u003e]+[a-z\\x00-\\x20\"\\\u0027\\/)(?:on[a-z]+)\\s*=[\\s|\\\u0027\"\u0027].*[\\s|\\\u0027\"\u0027]\u003e#iUu\u0027\n```\n\nrequires either quotes around the handler value or a trailing space before `\u003e`. An unquoted handler like `onerror=alert(1)\u003e` (no space before `\u003e`) bypasses this check entirely.\n\nCombined with `\u003c/option\u003e\u003c/select\u003e` to break out of the select context (neither tag is in `dangerous_tags`), the full payload evades all three detection layers and triggers no XSS warning in the admin panel.\n\n### PoC\n\n#### Step 1: Login as Editor\nNavigate to `http://TARGET/admin/` and authenticate with editor credentials.\n\n#### Step 2: Create a Page with Malicious Taxonomy\n- Go to Pages \u2192 Add \u2192 Add Page\n- Title: `XSS via editor`\n- Go to **Options** Tap\n- On Taxonomies, Add tag:\n```\n\u003c/option\u003e\u003c/select\u003e\u003cimg src=x onerror=alert(\u0027XSS-via-editor\u0027)\u003e\n```\n\nThis payload:\n- Closes `\u003c/option\u003e\u003c/select\u003e` to break out of the select dropdown context\n- Injects an `\u003cimg\u003e` tag with an unquoted `onerror` handler (bypasses `on_events` regex)\n- Is not in the `dangerous_tags` list (no `\u003cscript\u003e`, `\u003ciframe\u003e`, etc.)\n- Triggers no XSS warning in the admin panel\n\n\u003cimg width=\"1221\" height=\"857\" alt=\"image\" src=\"https://github.com/user-attachments/assets/6223cbb2-f04b-46bd-89ce-828c89ad77ab\" /\u003e\n\n#### Step 3: Trigger the XSS\nWhen any administrator navigates to the page editor of any page (not just the malicious one), the JavaScript executes immediately.\n\n\u003cimg width=\"1224\" height=\"856\" alt=\"image\" src=\"https://github.com/user-attachments/assets/f008b0f2-dedb-4b22-a74a-cdc0d7325cb4\" /\u003e\n\nThe XSS fires because taxonomy tag options are collected globally across all pages and rendered with `|raw` in the select dropdown template. The payload breaks out of the `\u003coption\u003e` context, and the browser renders the `\u003cimg\u003e` tag as a regular DOM element.\n\n### Impact\n\n- Session hijacking: While `HttpOnly` prevents direct cookie theft, the XSS can steal the admin nonce token and perform any admin action via AJAX requests\n- Privilege escalation: An editor can perform admin-only actions (create users, modify system configuration, install plugins) through the hijacked admin session\n- Cross-page impact: A single malicious taxonomy value affects the entire admin panel - every page editor view is compromised\n\n\n---\n\n## Maintainer note \u2014 fix applied (2026-04-24)\n\nFixed across two repos:\n\n1. **grav-plugin-form 9.0.1** (commit [`6bffb4c`](https://github.com/getgrav/grav-plugin-form/commit/6bffb4c)) \u2014 the primary fix. All four `|raw` filters in [`templates/forms/fields/select/select.html.twig`](https://github.com/getgrav/grav-plugin-form/blob/develop/templates/forms/fields/select/select.html.twig) (placeholder, avalue, suboption, item_value) have been removed. Option labels \u2014 including taxonomy values that propagate cross-page through the admin\u0027s shared selection pool \u2014 now go through Twig\u0027s default escaper, so a lower-privileged editor can no longer inject script that runs in an admin\u0027s browser when they open any page editor.\n\n2. **Grav core on the `2.0` branch** (commit [`5a12f9be8`](https://github.com/getgrav/grav/commit/5a12f9be8), ships in **2.0.0-beta.2**) \u2014 closes the detection-bypass half of the report. The `on_events` regex in `Security::detectXss()` is tightened so unquoted handlers like `onerror=alert(1)\u003e` are flagged (see separate GHSA-9695-8fr9-hw5q), and `option`/`select` have been added to default `security.xss_dangerous_tags` so `\u003c/option\u003e\u003c/select\u003e\u2026` tripwires the detector (see separate GHSA-w8cg-7jcj-4vv2).\n\nSites running admin2 on Grav 2.0.0-beta.2 get the 9.0.1 form plugin automatically via its existing dependency graph.\n\n**Files:**\n- [`templates/forms/fields/select/select.html.twig`](https://github.com/getgrav/grav-plugin-form/blob/develop/templates/forms/fields/select/select.html.twig) \u2014 four `|raw` removed.\n- [`system/config/security.yaml`](https://github.com/getgrav/grav/blob/2.0/system/config/security.yaml) \u2014 dangerous-tags list extended.\n- [`system/src/Grav/Common/Security.php`](https://github.com/getgrav/grav/blob/2.0/system/src/Grav/Common/Security.php) \u2014 `on_events` regex tightened.\n- [`tests/unit/Grav/Common/Security/DetectXssTest.php`](https://github.com/getgrav/grav/blob/2.0/tests/unit/Grav/Common/Security/DetectXssTest.php) \u2014 includes the GHSA-c2q3 PoC payload.",
"id": "GHSA-c2q3-p4jr-c55f",
"modified": "2026-05-13T14:04:28Z",
"published": "2026-05-05T21:24:45Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/getgrav/grav/security/advisories/GHSA-c2q3-p4jr-c55f"
},
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-42842"
},
{
"type": "WEB",
"url": "https://github.com/getgrav/grav-plugin-form/commit/6bffb4c98be468a155d1656544ec45bb4a443957"
},
{
"type": "WEB",
"url": "https://github.com/getgrav/grav/commit/5a12f9be8314682c8713e569e330f11805d0a663"
},
{
"type": "PACKAGE",
"url": "https://github.com/getgrav/grav"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N",
"type": "CVSS_V3"
}
],
"summary": "Grav Vulnerable to XSS via Taxonomy Field Values in Admin Panel"
}
Mitigation MIT-4
Strategy: Libraries or Frameworks
- Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid [REF-1482].
- Examples of libraries and frameworks that make it easier to generate properly encoded output include Microsoft's Anti-XSS library, the OWASP ESAPI Encoding module, and Apache Wicket.
Mitigation
- Understand the context in which your data will be used and the encoding that will be expected. This is especially important when transmitting data between different components, or when generating outputs that can contain multiple encodings at the same time, such as web pages or multi-part mail messages. Study all expected communication protocols and data representations to determine the required encoding strategies.
- For any data that will be output to another web page, especially any data that was received from external inputs, use the appropriate encoding on all non-alphanumeric characters.
- Parts of the same output document may require different encodings, which will vary depending on whether the output is in the:
- etc. Note that HTML Entity Encoding is only appropriate for the HTML body.
- Consult the XSS Prevention Cheat Sheet [REF-724] for more details on the types of encoding and escaping that are needed.
- HTML body
- Element attributes (such as src="XYZ")
- URIs
- JavaScript sections
- Cascading Style Sheets and style property
Mitigation MIT-6
Strategy: Attack Surface Reduction
Understand all the potential areas where untrusted inputs can enter your software: parameters or arguments, cookies, anything read from the network, environment variables, reverse DNS lookups, query results, request headers, URL components, e-mail, files, filenames, databases, and any external systems that provide data to the application. Remember that such inputs may be obtained indirectly through API calls.
Mitigation MIT-15
For any security checks that are performed on the client side, ensure that these checks are duplicated on the server side, in order to avoid CWE-602. Attackers can bypass the client-side checks by modifying values after the checks have been performed, or by changing the client to remove the client-side checks entirely. Then, these modified values would be submitted to the server.
Mitigation MIT-27
Strategy: Parameterization
If available, use structured mechanisms that automatically enforce the separation between data and code. These mechanisms may be able to provide the relevant quoting, encoding, and validation automatically, instead of relying on the developer to provide this capability at every point where output is generated.
Mitigation MIT-30.1
Strategy: Output Encoding
- Use and specify an output encoding that can be handled by the downstream component that is reading the output. Common encodings include ISO-8859-1, UTF-7, and UTF-8. When an encoding is not specified, a downstream component may choose a different encoding, either by assuming a default encoding or automatically inferring which encoding is being used, which can be erroneous. When the encodings are inconsistent, the downstream component might treat some character or byte sequences as special, even if they are not special in the original encoding. Attackers might then be able to exploit this discrepancy and conduct injection attacks; they even might be able to bypass protection mechanisms that assume the original encoding is also being used by the downstream component.
- The problem of inconsistent output encodings often arises in web pages. If an encoding is not specified in an HTTP header, web browsers often guess about which encoding is being used. This can open up the browser to subtle XSS attacks.
Mitigation MIT-43
With Struts, write all data from form beans with the bean's filter attribute set to true.
Mitigation MIT-31
Strategy: Attack Surface Reduction
To help mitigate XSS attacks against the user's session cookie, set the session cookie to be HttpOnly. In browsers that support the HttpOnly feature (such as more recent versions of Internet Explorer and Firefox), this attribute can prevent the user's session cookie from being accessible to malicious client-side scripts that use document.cookie. This is not a complete solution, since HttpOnly is not supported by all browsers. More importantly, XmlHttpRequest and other powerful browser technologies provide read access to HTTP headers, including the Set-Cookie header in which the HttpOnly flag is set.
Mitigation MIT-5
Strategy: Input Validation
- Assume all input is malicious. Use an "accept known good" input validation strategy, i.e., use a list of acceptable inputs that strictly conform to specifications. Reject any input that does not strictly conform to specifications, or transform it into something that does.
- When performing input validation, consider all potentially relevant properties, including length, type of input, the full range of acceptable values, missing or extra inputs, syntax, consistency across related fields, and conformance to business rules. As an example of business rule logic, "boat" may be syntactically valid because it only contains alphanumeric characters, but it is not valid if the input is only expected to contain colors such as "red" or "blue."
- Do not rely exclusively on looking for malicious or malformed inputs. This is likely to miss at least one undesirable input, especially if the code's environment changes. This can give attackers enough room to bypass the intended validation. However, denylists can be useful for detecting potential attacks or determining which inputs are so malformed that they should be rejected outright.
- When dynamically constructing web pages, use stringent allowlists that limit the character set based on the expected value of the parameter in the request. All input should be validated and cleansed, not just parameters that the user is supposed to specify, but all data in the request, including hidden fields, cookies, headers, the URL itself, and so forth. A common mistake that leads to continuing XSS vulnerabilities is to validate only fields that are expected to be redisplayed by the site. It is common to see data from the request that is reflected by the application server or the application that the development team did not anticipate. Also, a field that is not currently reflected may be used by a future developer. Therefore, validating ALL parts of the HTTP request is recommended.
- Note that proper output encoding, escaping, and quoting is the most effective solution for preventing XSS, although input validation may provide some defense-in-depth. This is because it effectively limits what will appear in output. Input validation will not always prevent XSS, especially if you are required to support free-form text fields that could contain arbitrary characters. For example, in a chat application, the heart emoticon ("<3") would likely pass the validation step, since it is commonly used. However, it cannot be directly inserted into the web page because it contains the "<" character, which would need to be escaped or otherwise handled. In this case, stripping the "<" might reduce the risk of XSS, but it would produce incorrect behavior because the emoticon would not be recorded. This might seem to be a minor inconvenience, but it would be more important in a mathematical forum that wants to represent inequalities.
- Even if you make a mistake in your validation (such as forgetting one out of 100 input fields), appropriate encoding is still likely to protect you from injection-based attacks. As long as it is not done in isolation, input validation is still a useful technique, since it may significantly reduce your attack surface, allow you to detect some attacks, and provide other security benefits that proper encoding does not address.
- Ensure that you perform input validation at well-defined interfaces within the application. This will help protect the application even if a component is reused or moved elsewhere.
Mitigation MIT-21
Strategy: Enforcement by Conversion
When the set of acceptable objects, such as filenames or URLs, is limited or known, create a mapping from a set of fixed input values (such as numeric IDs) to the actual filenames or URLs, and reject all other inputs.
Mitigation MIT-29
Strategy: Firewall
Use an application firewall that can detect attacks against this weakness. It can be beneficial in cases in which the code cannot be fixed (because it is controlled by a third party), as an emergency prevention measure while more comprehensive software assurance measures are applied, or to provide defense in depth [REF-1481].
Mitigation MIT-16
Strategy: Environment Hardening
When using PHP, configure the application so that it does not use register_globals. During implementation, develop the application so that it does not rely on this feature, but be wary of implementing a register_globals emulation that is subject to weaknesses such as CWE-95, CWE-621, and similar issues.
CAPEC-209: XSS Using MIME Type Mismatch
An adversary creates a file with scripting content but where the specified MIME type of the file is such that scripting is not expected. The adversary tricks the victim into accessing a URL that responds with the script file. Some browsers will detect that the specified MIME type of the file does not match the actual type of its content and will automatically switch to using an interpreter for the real content type. If the browser does not invoke script filters before doing this, the adversary's script may run on the target unsanitized, possibly revealing the victim's cookies or executing arbitrary script in their browser.
CAPEC-588: DOM-Based XSS
This type of attack is a form of Cross-Site Scripting (XSS) where a malicious script is inserted into the client-side HTML being parsed by a web browser. Content served by a vulnerable web application includes script code used to manipulate the Document Object Model (DOM). This script code either does not properly validate input, or does not perform proper output encoding, thus creating an opportunity for an adversary to inject a malicious script launch a XSS attack. A key distinction between other XSS attacks and DOM-based attacks is that in other XSS attacks, the malicious script runs when the vulnerable web page is initially loaded, while a DOM-based attack executes sometime after the page loads. Another distinction of DOM-based attacks is that in some cases, the malicious script is never sent to the vulnerable web server at all. An attack like this is guaranteed to bypass any server-side filtering attempts to protect users.
CAPEC-591: Reflected XSS
This type of attack is a form of Cross-Site Scripting (XSS) where a malicious script is "reflected" off a vulnerable web application and then executed by a victim's browser. The process starts with an adversary delivering a malicious script to a victim and convincing the victim to send the script to the vulnerable web application.
CAPEC-592: Stored XSS
An adversary utilizes a form of Cross-site Scripting (XSS) where a malicious script is persistently "stored" within the data storage of a vulnerable web application as valid input.
CAPEC-63: Cross-Site Scripting (XSS)
An adversary embeds malicious scripts in content that will be served to web browsers. The goal of the attack is for the target software, the client-side browser, to execute the script with the users' privilege level. An attack of this type exploits a programs' vulnerabilities that are brought on by allowing remote hosts to execute code and scripts. Web browsers, for example, have some simple security controls in place, but if a remote attacker is allowed to execute scripts (through injecting them in to user-generated content like bulletin boards) then these controls may be bypassed. Further, these attacks are very difficult for an end user to detect.
CAPEC-85: AJAX Footprinting
This attack utilizes the frequent client-server roundtrips in Ajax conversation to scan a system. While Ajax does not open up new vulnerabilities per se, it does optimize them from an attacker point of view. A common first step for an attacker is to footprint the target environment to understand what attacks will work. Since footprinting relies on enumeration, the conversational pattern of rapid, multiple requests and responses that are typical in Ajax applications enable an attacker to look for many vulnerabilities, well-known ports, network locations and so on. The knowledge gained through Ajax fingerprinting can be used to support other attacks, such as XSS.