CWE-80
AllowedImproper Neutralization of Script-Related HTML Tags in a Web Page (Basic XSS)
Abstraction: Variant · Status: Incomplete
The product receives input from an upstream component, but it does not neutralize or incorrectly neutralizes special characters such as "<", ">", and "&" that could be interpreted as web-scripting elements when they are sent to a downstream component that processes web pages.
975 vulnerabilities reference this CWE, most recent first.
GHSA-8CM9-GX9F-Q3WM
Vulnerability from github – Published: 2026-01-07 12:31 – Updated: 2026-01-07 12:31The Key Figures plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the kf_field_figure_default_color_render function in all versions up to, and including, 1.1 due to insufficient input sanitization and output escaping. This makes it possible for authenticated attackers, with administrator-level access, to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page. This only affects multi-site installations and installations where unfiltered_html has been disabled.
{
"affected": [],
"aliases": [
"CVE-2025-14792"
],
"database_specific": {
"cwe_ids": [
"CWE-80"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-01-07T12:16:56Z",
"severity": "MODERATE"
},
"details": "The Key Figures plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the kf_field_figure_default_color_render function in all versions up to, and including, 1.1 due to insufficient input sanitization and output escaping. This makes it possible for authenticated attackers, with administrator-level access, to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page. This only affects multi-site installations and installations where unfiltered_html has been disabled.",
"id": "GHSA-8cm9-gx9f-q3wm",
"modified": "2026-01-07T12:31:23Z",
"published": "2026-01-07T12:31:23Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2025-14792"
},
{
"type": "WEB",
"url": "https://www.wordfence.com/threat-intel/vulnerabilities/id/f4943899-a25a-4e50-b33e-139ed5e8f748?source=cve"
},
{
"type": "WEB",
"url": "http://plugins.trac.wordpress.org/browser/key-figures/tags/1.1/admin/kf-admin.php#L201"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:C/C:L/I:L/A:N",
"type": "CVSS_V3"
}
]
}
GHSA-8F2F-6W9M-MG42
Vulnerability from github – Published: 2026-02-11 12:30 – Updated: 2026-02-11 12:30GitLab has remediated an issue in GitLab CE/EE affecting all versions from 18.6 before 18.6.6, 18.7 before 18.7.4, and 18.8 before 18.8.4 that could have allowed an authenticated user to inject malicious content into project labels titles.
{
"affected": [],
"aliases": [
"CVE-2026-1282"
],
"database_specific": {
"cwe_ids": [
"CWE-80"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-02-11T12:16:04Z",
"severity": "LOW"
},
"details": "GitLab has remediated an issue in GitLab CE/EE affecting all versions from 18.6 before 18.6.6, 18.7 before 18.7.4, and 18.8 before 18.8.4 that could have allowed an authenticated user to inject malicious content into project labels titles.",
"id": "GHSA-8f2f-6w9m-mg42",
"modified": "2026-02-11T12:30:22Z",
"published": "2026-02-11T12:30:22Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-1282"
},
{
"type": "WEB",
"url": "https://hackerone.com/reports/3505596"
},
{
"type": "WEB",
"url": "https://about.gitlab.com/releases/2026/02/10/patch-release-gitlab-18-8-4-released"
},
{
"type": "WEB",
"url": "https://gitlab.com/gitlab-org/gitlab/-/issues/587106"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:N/I:L/A:N",
"type": "CVSS_V3"
}
]
}
GHSA-8FXQ-MGG4-PXG6
Vulnerability from github – Published: 2024-07-03 18:48 – Updated: 2024-07-03 18:48Stored XSS in Checkmk before versions 2.3.0p8, 2.2.0p29, 2.1.0p45, and 2.0.0 (EOL) allows users to execute arbitrary scripts by injecting HTML elements
{
"affected": [],
"aliases": [
"CVE-2024-6052"
],
"database_specific": {
"cwe_ids": [
"CWE-79",
"CWE-80"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2024-07-03T15:15:06Z",
"severity": "MODERATE"
},
"details": "Stored XSS in Checkmk before versions 2.3.0p8, 2.2.0p29, 2.1.0p45, and 2.0.0 (EOL) allows users to execute arbitrary scripts by injecting HTML elements",
"id": "GHSA-8fxq-mgg4-pxg6",
"modified": "2024-07-03T18:48:25Z",
"published": "2024-07-03T18:48:25Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2024-6052"
},
{
"type": "WEB",
"url": "https://checkmk.com/werk/17010"
}
],
"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-8HV8-536X-4WQP
Vulnerability from github – Published: 2026-06-16 14:05 – Updated: 2026-08-12 20:37Summary
When a component uses a client:* directive, Astro inserts named slot content into a data-astro-template attribute without HTML escaping the slot name allowing an attacker to break out of the attribute context and inject arbitrary HTML, resulting in reflected XSS during SSR.
This is similar to GHSA-wrwg-2hg8-v723 but exploits a different injection point.
Vulnerable Code
packages/astro/src/runtime/server/render/component.ts:371:376
// component.ts:371
`<template data-astro-template${key !== 'default' ? `="${key}"` : ''}>${children[key]}</template>`
I found that key is interpolated directly into the attribute value without proper escaping.
Proof of Concept
For the PoC, I set up with a minimal repository with Astro 6.3.1, Node.js: v26.0.0.
astro.config.mjs
import react from '@astrojs/react';
import node from '@astrojs/node';
import { defineConfig } from 'astro/config';
export default defineConfig({
output: 'server',
adapter: node({ mode: 'standalone' }),
integrations: [react()],
});
src/pages/index.astro
---
import Wrapper from '../components/Wrapper.jsx';
const slotName = Astro.url.searchParams.get('tab') ?? 'default';
---
<html><body>
<Wrapper client:load>
<div slot={slotName}>content</div>
</Wrapper>
</body></html>
src/components/Wrapper.jsx
export default function Wrapper() { return null; }
Payload:
abc"></template></astro-island><img src=x onerror=confirm(document.domain)><!--
Accessing this URL will trigger the popup.
http://localhost:4321/?tab=abc%22%3E%3C%2Ftemplate%3E%3C%2Fastro-island%3E%3Cimg+src%3Dx+onerror%3Dconfirm(document.domain)%3E%3C!--
This will render in html.
<template data-astro-template="abc"></template></astro-island>
<img src=x onerror=confirm(document.domain)><!--">content</template>
Fix
I suggest leveraging the existing escape function on the slot name.
// component.ts:371
`<template data-astro-template${key !== 'default' ? `="${escapeHTML(String(key))}"` : ''}>${children[key]}</template>`
{
"affected": [
{
"package": {
"ecosystem": "npm",
"name": "astro"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "6.3.3"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [
"CVE-2026-50146"
],
"database_specific": {
"cwe_ids": [
"CWE-79",
"CWE-80"
],
"github_reviewed": true,
"github_reviewed_at": "2026-06-16T14:05:06Z",
"nvd_published_at": "2026-06-22T19:17:04Z",
"severity": "HIGH"
},
"details": "## Summary\n\nWhen a component uses a `client:*` directive, Astro inserts named slot content into a `data-astro-template` attribute without HTML escaping the slot name allowing an attacker to break out of the attribute context and inject arbitrary HTML, resulting in reflected XSS during SSR.\n\nThis is similar to GHSA-wrwg-2hg8-v723 but exploits a different injection point.\n\n## Vulnerable Code\n\n`packages/astro/src/runtime/server/render/component.ts:371:376`\n\n```ts\n// component.ts:371\n`\u003ctemplate data-astro-template${key !== \u0027default\u0027 ? `=\"${key}\"` : \u0027\u0027}\u003e${children[key]}\u003c/template\u003e`\n```\n\nI found that key is interpolated directly into the attribute value without proper escaping.\n\n## Proof of Concept\n\nFor the PoC, I set up with a minimal repository with Astro 6.3.1, Node.js: v26.0.0.\n\n**`astro.config.mjs`**\n```js\nimport react from \u0027@astrojs/react\u0027;\nimport node from \u0027@astrojs/node\u0027;\nimport { defineConfig } from \u0027astro/config\u0027;\nexport default defineConfig({\n output: \u0027server\u0027,\n adapter: node({ mode: \u0027standalone\u0027 }),\n integrations: [react()],\n});\n```\n\n**`src/pages/index.astro`**\n```astro\n---\nimport Wrapper from \u0027../components/Wrapper.jsx\u0027;\nconst slotName = Astro.url.searchParams.get(\u0027tab\u0027) ?? \u0027default\u0027;\n---\n\u003chtml\u003e\u003cbody\u003e\n \u003cWrapper client:load\u003e\n \u003cdiv slot={slotName}\u003econtent\u003c/div\u003e\n \u003c/Wrapper\u003e\n\u003c/body\u003e\u003c/html\u003e\n```\n\n**`src/components/Wrapper.jsx`**\n```jsx\nexport default function Wrapper() { return null; }\n```\n\n**Payload:**\n```\nabc\"\u003e\u003c/template\u003e\u003c/astro-island\u003e\u003cimg src=x onerror=confirm(document.domain)\u003e\u003c!--\n```\nAccessing this URL will trigger the popup.\n\nhttp://localhost:4321/?tab=abc%22%3E%3C%2Ftemplate%3E%3C%2Fastro-island%3E%3Cimg+src%3Dx+onerror%3Dconfirm(document.domain)%3E%3C!--\n\n\n\n\u003cimg width=\"1268\" height=\"592\" alt=\"image\" src=\"https://github.com/user-attachments/assets/675cdc04-4134-4d83-883c-abe16d751ec7\" /\u003e\n\n\n\nThis will render in html.\n\n```html\n\u003ctemplate data-astro-template=\"abc\"\u003e\u003c/template\u003e\u003c/astro-island\u003e\n\u003cimg src=x onerror=confirm(document.domain)\u003e\u003c!--\"\u003econtent\u003c/template\u003e\n```\n\n## Fix\n\nI suggest leveraging the existing escape function on the slot name.\n\n```ts\n// component.ts:371\n`\u003ctemplate data-astro-template${key !== \u0027default\u0027 ? `=\"${escapeHTML(String(key))}\"` : \u0027\u0027}\u003e${children[key]}\u003c/template\u003e`\n```\n\n---",
"id": "GHSA-8hv8-536x-4wqp",
"modified": "2026-08-12T20:37:18Z",
"published": "2026-06-16T14:05:06Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/withastro/astro/security/advisories/GHSA-8hv8-536x-4wqp"
},
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-50146"
},
{
"type": "PACKAGE",
"url": "https://github.com/withastro/astro"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:H/A:N",
"type": "CVSS_V3"
}
],
"summary": "Astro: Reflected XSS via unescaped slot name"
}
GHSA-8M7P-5M49-8XXM
Vulnerability from github – Published: 2024-06-18 12:30 – Updated: 2024-06-18 12:30A vulnerability was found in Genexis Tilgin Home Gateway 322_AS0500-03_05_13_05. It has been classified as problematic. Affected is an unknown function of the file /vood/cgi-bin/vood_view.cgi?act=index&lang=EN# of the component Login. The manipulation of the argument errmsg leads to basic cross site scripting. It is possible to launch the attack remotely. VDB-268854 is the identifier assigned to this vulnerability. NOTE: The vendor was contacted early about this disclosure but did not respond in any way.
{
"affected": [],
"aliases": [
"CVE-2024-6108"
],
"database_specific": {
"cwe_ids": [
"CWE-80"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2024-06-18T10:15:11Z",
"severity": "MODERATE"
},
"details": "A vulnerability was found in Genexis Tilgin Home Gateway 322_AS0500-03_05_13_05. It has been classified as problematic. Affected is an unknown function of the file /vood/cgi-bin/vood_view.cgi?act=index\u0026lang=EN# of the component Login. The manipulation of the argument errmsg leads to basic cross site scripting. It is possible to launch the attack remotely. VDB-268854 is the identifier assigned to this vulnerability. NOTE: The vendor was contacted early about this disclosure but did not respond in any way.",
"id": "GHSA-8m7p-5m49-8xxm",
"modified": "2024-06-18T12:30:41Z",
"published": "2024-06-18T12:30:41Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2024-6108"
},
{
"type": "WEB",
"url": "https://vuldb.com/?ctiid.268854"
},
{
"type": "WEB",
"url": "https://vuldb.com/?id.268854"
},
{
"type": "WEB",
"url": "https://vuldb.com/?submit.353708"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:N",
"type": "CVSS_V3"
}
]
}
GHSA-8P46-C7VP-CVJ5
Vulnerability from github – Published: 2024-05-17 09:31 – Updated: 2024-05-17 09:31Improper Neutralization of Script-Related HTML Tags in a Web Page (Basic XSS) vulnerability in Strategy11 Form Builder Team Formidable Forms allows Code Injection.This issue affects Formidable Forms: from n/a through 6.7.
{
"affected": [],
"aliases": [
"CVE-2024-23522"
],
"database_specific": {
"cwe_ids": [
"CWE-79",
"CWE-80"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2024-05-17T09:15:22Z",
"severity": "MODERATE"
},
"details": "Improper Neutralization of Script-Related HTML Tags in a Web Page (Basic XSS) vulnerability in Strategy11 Form Builder Team Formidable Forms allows Code Injection.This issue affects Formidable Forms: from n/a through 6.7.",
"id": "GHSA-8p46-c7vp-cvj5",
"modified": "2024-05-17T09:31:02Z",
"published": "2024-05-17T09:31:02Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2024-23522"
},
{
"type": "WEB",
"url": "https://patchstack.com/database/vulnerability/formidable/wordpress-formidable-forms-plugin-6-7-content-injection-vulnerability?_s_id=cve"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N",
"type": "CVSS_V3"
}
]
}
GHSA-8PCC-94CG-8PR4
Vulnerability from github – Published: 2022-06-30 00:00 – Updated: 2022-07-09 00:00A vulnerability was found in TrueConf Server 4.3.7 and classified as problematic. This issue affects some unknown processing of the file /admin/conferences/list/. The manipulation of the argument sort leads to basic cross site scripting (Reflected). The attack may be initiated remotely. The exploit has been disclosed to the public and may be used.
{
"affected": [],
"aliases": [
"CVE-2017-20115"
],
"database_specific": {
"cwe_ids": [
"CWE-79",
"CWE-80"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2022-06-29T17:15:00Z",
"severity": "MODERATE"
},
"details": "A vulnerability was found in TrueConf Server 4.3.7 and classified as problematic. This issue affects some unknown processing of the file /admin/conferences/list/. The manipulation of the argument sort leads to basic cross site scripting (Reflected). The attack may be initiated remotely. The exploit has been disclosed to the public and may be used.",
"id": "GHSA-8pcc-94cg-8pr4",
"modified": "2022-07-09T00:00:19Z",
"published": "2022-06-30T00:00:34Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2017-20115"
},
{
"type": "WEB",
"url": "https://vuldb.com/?id.96629"
},
{
"type": "WEB",
"url": "https://www.exploit-db.com/exploits/41184"
}
],
"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-8PP6-VXQ4-65QV
Vulnerability from github – Published: 2022-08-11 00:00 – Updated: 2022-08-13 00:00An issue was discovered in EyouCMS 1.5.8. There is a Storage XSS vulnerability that can allows an attacker to execute arbitrary Web scripts or HTML by injecting a special payload via the title parameter in the foreground contribution, allowing the attacker to obtain sensitive information.
{
"affected": [],
"aliases": [
"CVE-2022-35509"
],
"database_specific": {
"cwe_ids": [
"CWE-79",
"CWE-80"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2022-08-10T20:15:00Z",
"severity": "MODERATE"
},
"details": "An issue was discovered in EyouCMS 1.5.8. There is a Storage XSS vulnerability that can allows an attacker to execute arbitrary Web scripts or HTML by injecting a special payload via the title parameter in the foreground contribution, allowing the attacker to obtain sensitive information.",
"id": "GHSA-8pp6-vxq4-65qv",
"modified": "2022-08-13T00:00:25Z",
"published": "2022-08-11T00:00:18Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2022-35509"
},
{
"type": "WEB",
"url": "https://github.com/eyoucms/eyoucms/issues/25"
}
],
"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-8QWG-H3WF-MWX5
Vulnerability from github – Published: 2024-01-02 00:30 – Updated: 2024-01-02 00:30A vulnerability was found in RRJ Nueva Ecija Engineer Online Portal 1.0. It has been classified as problematic. This affects an unknown part of the file /admin/students.php of the component NIA Office. The manipulation leads to basic cross site scripting. It is possible to initiate the attack remotely. The exploit has been disclosed to the public and may be used. The identifier VDB-249441 was assigned to this vulnerability.
{
"affected": [],
"aliases": [
"CVE-2024-0183"
],
"database_specific": {
"cwe_ids": [
"CWE-80"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2024-01-01T23:15:08Z",
"severity": "LOW"
},
"details": "A vulnerability was found in RRJ Nueva Ecija Engineer Online Portal 1.0. It has been classified as problematic. This affects an unknown part of the file /admin/students.php of the component NIA Office. The manipulation leads to basic cross site scripting. It is possible to initiate the attack remotely. The exploit has been disclosed to the public and may be used. The identifier VDB-249441 was assigned to this vulnerability.",
"id": "GHSA-8qwg-h3wf-mwx5",
"modified": "2024-01-02T00:30:21Z",
"published": "2024-01-02T00:30:21Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2024-0183"
},
{
"type": "WEB",
"url": "https://mega.nz/file/SB8ylCxQ#vSaXJwbNjeG-KXatgkxE8XI6Cmnv-A_Sg2IjvoJZs0E"
},
{
"type": "WEB",
"url": "https://vuldb.com/?ctiid.249441"
},
{
"type": "WEB",
"url": "https://vuldb.com/?id.249441"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:U/C:N/I:L/A:N",
"type": "CVSS_V3"
}
]
}
GHSA-8RQ5-WWPP-FMJ2
Vulnerability from github – Published: 2026-05-05 20:32 – Updated: 2026-05-13 16:24Description: Stored Cross-Site Scripting (XSS) occurs when user-supplied input is persisted by the application and later rendered in another user's browser without proper sanitization or contextual output encoding. When the vulnerable sink is a high-traffic surface such as a public forum thread, the payload executes in the browser of every user who visits the page, maximizing both reach and impact. Any JavaScript injected through such a sink runs under the application's origin and inherits the privileges of whichever user happens to view the affected content.
Issue Details:
The thread posting and reply feature accepts user-supplied content that is stored server-side and later rendered back into the thread page without adequate HTML sanitization or contextual output encoding. Submitting a post or reply containing "><img src=x onerror=prompt(0)> causes the payload to break out of the surrounding HTML context and inject a fully attacker-controlled <img> element whose onerror handler fires automatically as soon as the broken image reference fails to load. Because posts and replies are visible to every user who visits the thread, authenticated or otherwise, the injected JavaScript executes in each viewer's browser the moment the page renders, with no additional interaction required.
Impact: An attacker with a standard forum account can execute arbitrary JavaScript in the browser of every user who loads the affected thread, including moderators and administrators. This enables session/auth-cookie theft, account takeover through same-origin state-changing requests, forced privileged actions if an administrator views the thread, credential phishing via injected login overlays, forum defacement, cryptominer or malware delivery, and mass redirection of viewers to attacker-controlled sites. Because the payload triggers automatically on page load rather than requiring hover or click interaction, a single malicious post can compromise a large number of users very quickly.
Likelihood: Exploitation requires only a registered account with permission to post or reply, which is available to every forum member by default. Once posted, the payload fires automatically for any visitor who opens the thread, requiring zero victim interaction and making the overall likelihood high.
Steps to Reproduce:
- Log in to the forum as any low-privileged user (Attacker).
- Navigate to any thread where posting or replying is allowed, or create a new thread.
- In the post/reply body, submit the payload: "><img src=x onerror=prompt(0)>
- Publish the post or reply.
- Log in as a different user (e.g., Admin) or visit the thread in a separate browser session.
- Open the thread page, the injected <img> fails to load and the onerror handler fires, producing a prompt(0) dialog and confirming arbitrary JavaScript execution in the viewer's session context.
{
"affected": [
{
"database_specific": {
"last_known_affected_version_range": "\u003c= 4.0.4"
},
"package": {
"ecosystem": "NuGet",
"name": "YAFNET.Core"
},
"ranges": [
{
"events": [
{
"introduced": "4.0.0-beta01"
},
{
"fixed": "4.0.5"
}
],
"type": "ECOSYSTEM"
}
]
},
{
"database_specific": {
"last_known_affected_version_range": "\u003c= 3.2.11"
},
"package": {
"ecosystem": "NuGet",
"name": "YAFNET.Core"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "3.2.12"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [
"CVE-2026-43939"
],
"database_specific": {
"cwe_ids": [
"CWE-116",
"CWE-79",
"CWE-80"
],
"github_reviewed": true,
"github_reviewed_at": "2026-05-05T20:32:47Z",
"nvd_published_at": "2026-05-12T15:16:15Z",
"severity": "HIGH"
},
"details": "**Description:**\nStored Cross-Site Scripting (XSS) occurs when user-supplied input is persisted by the application and later rendered in another user\u0027s browser without proper sanitization or contextual output encoding. When the vulnerable sink is a high-traffic surface such as a public forum thread, the payload executes in the browser of every user who visits the page, maximizing both reach and impact. Any JavaScript injected through such a sink runs under the application\u0027s origin and inherits the privileges of whichever user happens to view the affected content.\n\n**Issue Details:**\nThe thread posting and reply feature accepts user-supplied content that is stored server-side and later rendered back into the thread page without adequate HTML sanitization or contextual output encoding. Submitting a post or reply containing `\"\u003e\u003cimg src=x onerror=prompt(0)\u003e` causes the payload to break out of the surrounding HTML context and inject a fully attacker-controlled `\u003cimg\u003e` element whose `onerror` handler fires automatically as soon as the broken image reference fails to load. Because posts and replies are visible to every user who visits the thread, authenticated or otherwise, the injected JavaScript executes in each viewer\u0027s browser the moment the page renders, with no additional interaction required.\n\n**Impact:**\nAn attacker with a standard forum account can execute arbitrary JavaScript in the browser of every user who loads the affected thread, including moderators and administrators. This enables session/auth-cookie theft, account takeover through same-origin state-changing requests, forced privileged actions if an administrator views the thread, credential phishing via injected login overlays, forum defacement, cryptominer or malware delivery, and mass redirection of viewers to attacker-controlled sites. Because the payload triggers automatically on page load rather than requiring hover or click interaction, a single malicious post can compromise a large number of users very quickly.\n\n**Likelihood:**\nExploitation requires only a registered account with permission to post or reply, which is available to every forum member by default. Once posted, the payload fires automatically for any visitor who opens the thread, requiring zero victim interaction and making the overall likelihood high.\n\n**Steps to Reproduce:**\n- Log in to the forum as any low-privileged user (Attacker).\n- Navigate to any thread where posting or replying is allowed, or create a new thread.\n- In the post/reply body, submit the payload: `\"\u003e\u003cimg src=x onerror=prompt(0)\u003e`\n- Publish the post or reply.\n- Log in as a different user (e.g., Admin) or visit the thread in a separate browser session.\n- Open the thread page, the injected `\u003cimg\u003e` fails to load and the `onerror` handler fires, producing a `prompt(0)` dialog and confirming arbitrary JavaScript execution in the viewer\u0027s session context.\n\u003cimg width=\"1127\" height=\"745\" alt=\"image\" src=\"https://github.com/user-attachments/assets/b93442ea-1d8e-4079-ab4f-e52d41d110f3\" /\u003e",
"id": "GHSA-8rq5-wwpp-fmj2",
"modified": "2026-05-13T16:24:29Z",
"published": "2026-05-05T20:32:47Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/YAFNET/YAFNET/security/advisories/GHSA-8rq5-wwpp-fmj2"
},
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-43939"
},
{
"type": "PACKAGE",
"url": "https://github.com/YAFNET/YAFNET"
},
{
"type": "WEB",
"url": "https://github.com/YAFNET/YAFNET/releases/tag/v3.2.12"
},
{
"type": "WEB",
"url": "https://github.com/YAFNET/YAFNET/releases/tag/v4.0.5"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:N",
"type": "CVSS_V3"
}
],
"summary": "YAFNET has Stored XSS in Forum Thread Posts/Replies that Allows Arbitrary JavaScript Execution for All Thread Viewers"
}
Mitigation
Carefully check each input parameter against a rigorous positive specification (allowlist) defining the specific characters and format allowed. All input should be neutralized, 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. We often encounter 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.
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.
CAPEC-18: XSS Targeting Non-Script Elements
This attack is a form of Cross-Site Scripting (XSS) where malicious scripts are embedded in elements that are not expected to host scripts such as image tags (<img>), comments in XML documents (< !-CDATA->), etc. These tags may not be subject to the same input validation, output validation, and other content filtering and checking routines, so this can create an opportunity for an adversary to tunnel through the application's elements and launch a XSS attack through other elements. As with all remote attacks, it is important to differentiate the ability to launch an attack (such as probing an internal network for unpatched servers) and the ability of the remote adversary to collect and interpret the output of said attack.
CAPEC-193: PHP Remote File Inclusion
In this pattern the adversary is able to load and execute arbitrary code remotely available from the application. This is usually accomplished through an insecurely configured PHP runtime environment and an improperly sanitized "include" or "require" call, which the user can then control to point to any web-accessible file. This allows adversaries to hijack the targeted application and force it to execute their own instructions.
CAPEC-32: XSS Through HTTP Query Strings
An adversary embeds malicious script code in the parameters of an HTTP query string and convinces a victim to submit the HTTP request that contains the query string to a vulnerable web application. The web application then procedes to use the values parameters without properly validation them first and generates the HTML code that will be executed by the victim's browser.
CAPEC-86: XSS Through HTTP Headers
An adversary exploits web applications that generate web content, such as links in a HTML page, based on unvalidated or improperly validated data submitted by other actors. XSS in HTTP Headers attacks target the HTTP headers which are hidden from most users and may not be validated by web applications.