CWE-434
AllowedUnrestricted Upload of File with Dangerous Type
Abstraction: Base · Status: Draft
The product allows the upload or transfer of dangerous file types that are automatically processed within its environment.
5971 vulnerabilities reference this CWE, most recent first.
GHSA-3C7G-7R78-C425
Vulnerability from github – Published: 2024-08-12 15:30 – Updated: 2024-11-06 00:31An arbitrary file upload vulnerability in the Ueditor component of productinfoquick v1.0 allows attackers to execute arbitrary code via uploading a crafted PNG file.
{
"affected": [],
"aliases": [
"CVE-2024-41577"
],
"database_specific": {
"cwe_ids": [
"CWE-434"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2024-08-12T13:38:31Z",
"severity": "CRITICAL"
},
"details": "An arbitrary file upload vulnerability in the Ueditor component of productinfoquick v1.0 allows attackers to execute arbitrary code via uploading a crafted PNG file.",
"id": "GHSA-3c7g-7r78-c425",
"modified": "2024-11-06T00:31:54Z",
"published": "2024-08-12T15:30:50Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2024-41577"
},
{
"type": "WEB",
"url": "https://github.com/SENVIEL/learun-upload_file/issues/1"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
"type": "CVSS_V3"
}
]
}
GHSA-3CC8-7XHW-X4W6
Vulnerability from github – Published: 2024-06-13 15:30 – Updated: 2024-06-13 15:30Verint - CWE-434: Unrestricted Upload of File with Dangerous Type
{
"affected": [],
"aliases": [
"CVE-2024-36396"
],
"database_specific": {
"cwe_ids": [
"CWE-434"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2024-06-13T13:15:50Z",
"severity": "HIGH"
},
"details": "Verint - CWE-434: Unrestricted Upload of File with Dangerous Type",
"id": "GHSA-3cc8-7xhw-x4w6",
"modified": "2024-06-13T15:30:35Z",
"published": "2024-06-13T15:30:35Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2024-36396"
},
{
"type": "WEB",
"url": "https://www.gov.il/en/Departments/faq/cve_advisories"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
"type": "CVSS_V3"
}
]
}
GHSA-3CCQ-5VW3-2P6X
Vulnerability from github – Published: 2021-08-25 14:47 – Updated: 2022-02-08 20:44Impact
The vulnerability may allow a remote attacker to load and execute arbitrary code from a remote host only by manipulating the processed input stream. No user is affected, who followed the recommendation to setup XStream's security framework with a whitelist limited to the minimal required types.
Patches
XStream 1.4.18 uses no longer a blacklist by default, since it cannot be secured for general purpose.
Workarounds
See workarounds for the different versions covering all CVEs.
References
See full information about the nature of the vulnerability and the steps to reproduce it in XStream's documentation for CVE-2021-39149.
Credits
Lai Han of NSFOCUS security team found and reported the issue to XStream and provided the required information to reproduce it.
For more information
If you have any questions or comments about this advisory: * Open an issue in XStream * Contact us at XStream Google Group
{
"affected": [
{
"package": {
"ecosystem": "Maven",
"name": "com.thoughtworks.xstream:xstream"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "1.4.18"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [
"CVE-2021-39149"
],
"database_specific": {
"cwe_ids": [
"CWE-434",
"CWE-502"
],
"github_reviewed": true,
"github_reviewed_at": "2021-08-23T18:22:21Z",
"nvd_published_at": "2021-08-23T18:15:00Z",
"severity": "HIGH"
},
"details": "### Impact\nThe vulnerability may allow a remote attacker to load and execute arbitrary code from a remote host only by manipulating the processed input stream. No user is affected, who followed the recommendation to setup XStream\u0027s security framework with a whitelist limited to the minimal required types.\n\n### Patches\nXStream 1.4.18 uses no longer a blacklist by default, since it cannot be secured for general purpose.\n\n### Workarounds\nSee [workarounds](https://x-stream.github.io/security.html#workaround) for the different versions covering all CVEs.\n\n### References\nSee full information about the nature of the vulnerability and the steps to reproduce it in XStream\u0027s documentation for [CVE-2021-39149](https://x-stream.github.io/CVE-2021-39149.html).\n\n### Credits\nLai Han of NSFOCUS security team found and reported the issue to XStream and provided the required information to reproduce it.\n\n### For more information\nIf you have any questions or comments about this advisory:\n* Open an issue in [XStream](https://github.com/x-stream/xstream/issues)\n* Contact us at [XStream Google Group](https://groups.google.com/group/xstream-user)\n",
"id": "GHSA-3ccq-5vw3-2p6x",
"modified": "2022-02-08T20:44:12Z",
"published": "2021-08-25T14:47:28Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/x-stream/xstream/security/advisories/GHSA-3ccq-5vw3-2p6x"
},
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2021-39149"
},
{
"type": "PACKAGE",
"url": "https://github.com/x-stream/xstream"
},
{
"type": "WEB",
"url": "https://lists.debian.org/debian-lts-announce/2021/09/msg00017.html"
},
{
"type": "WEB",
"url": "https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/22KVR6B5IZP3BGQ3HPWIO2FWWCKT3DHP"
},
{
"type": "WEB",
"url": "https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/PVPHZA7VW2RRSDCOIPP2W6O5ND254TU7"
},
{
"type": "WEB",
"url": "https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/QGXIU3YDPG6OGTDHMBLAFN7BPBERXREB"
},
{
"type": "WEB",
"url": "https://security.netapp.com/advisory/ntap-20210923-0003"
},
{
"type": "WEB",
"url": "https://www.debian.org/security/2021/dsa-5004"
},
{
"type": "WEB",
"url": "https://www.oracle.com/security-alerts/cpuapr2022.html"
},
{
"type": "WEB",
"url": "https://www.oracle.com/security-alerts/cpujan2022.html"
},
{
"type": "WEB",
"url": "https://www.oracle.com/security-alerts/cpujul2022.html"
},
{
"type": "WEB",
"url": "https://x-stream.github.io/CVE-2021-39149.html"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:H",
"type": "CVSS_V3"
}
],
"summary": "XStream is vulnerable to an Arbitrary Code Execution attack"
}
GHSA-3CM8-C447-7FW4
Vulnerability from github – Published: 2025-03-09 06:31 – Updated: 2025-03-09 06:31A vulnerability, which was classified as critical, was found in zzskzy Warehouse Refinement Management System 3.1. Affected is the function ProcessRequest of the file /AcceptZip.ashx. The manipulation of the argument file leads to unrestricted upload. It is possible to launch the attack remotely. The exploit has been disclosed to the public and may be used. The vendor was contacted early about this disclosure but did not respond in any way.
{
"affected": [],
"aliases": [
"CVE-2025-2115"
],
"database_specific": {
"cwe_ids": [
"CWE-284",
"CWE-434"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2025-03-09T06:15:11Z",
"severity": "MODERATE"
},
"details": "A vulnerability, which was classified as critical, was found in zzskzy Warehouse Refinement Management System 3.1. Affected is the function ProcessRequest of the file /AcceptZip.ashx. The manipulation of the argument file leads to unrestricted upload. It is possible to launch the attack remotely. The exploit has been disclosed to the public and may be used. The vendor was contacted early about this disclosure but did not respond in any way.",
"id": "GHSA-3cm8-c447-7fw4",
"modified": "2025-03-09T06:31:42Z",
"published": "2025-03-09T06:31:42Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2025-2115"
},
{
"type": "WEB",
"url": "https://github.com/heiheixz/report/blob/main/sk_1.md"
},
{
"type": "WEB",
"url": "https://vuldb.com/?ctiid.299010"
},
{
"type": "WEB",
"url": "https://vuldb.com/?id.299010"
},
{
"type": "WEB",
"url": "https://vuldb.com/?submit.506655"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:L",
"type": "CVSS_V3"
},
{
"score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X",
"type": "CVSS_V4"
}
]
}
GHSA-3CPR-2H94-J6QJ
Vulnerability from github – Published: 2026-07-07 18:30 – Updated: 2026-07-07 18:30Vtiger CRM before 8.4.0 contains an authenticated file upload vulnerability that allows low-privileged users to achieve remote code execution by uploading a .phar file containing arbitrary PHP code through the Documents module, bypassing the extension denylist in config.inc.php which omits the .phar extension. The uploaded file is stored with its original .phar extension under the web-accessible storage directory, and a misconfigured .htaccess using Apache 2.2 syntax is silently ignored on Apache 2.4 deployments, allowing unauthenticated HTTP requests to directly execute the uploaded PHP payload.
{
"affected": [],
"aliases": [
"CVE-2026-23697"
],
"database_specific": {
"cwe_ids": [
"CWE-434"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-07-07T17:16:35Z",
"severity": "HIGH"
},
"details": "Vtiger CRM before 8.4.0 contains an authenticated file upload vulnerability that allows low-privileged users to achieve remote code execution by uploading a .phar file containing arbitrary PHP code through the Documents module, bypassing the extension denylist in config.inc.php which omits the .phar extension. The uploaded file is stored with its original .phar extension under the web-accessible storage directory, and a misconfigured .htaccess using Apache 2.2 syntax is silently ignored on Apache 2.4 deployments, allowing unauthenticated HTTP requests to directly execute the uploaded PHP payload.",
"id": "GHSA-3cpr-2h94-j6qj",
"modified": "2026-07-07T18:30:43Z",
"published": "2026-07-07T18:30:43Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-23697"
},
{
"type": "WEB",
"url": "https://jivasecurity.com/writeups/vtiger-rce-phar-upload-cve-2026-23697"
},
{
"type": "WEB",
"url": "https://www.vtiger.com"
},
{
"type": "WEB",
"url": "https://www.vulncheck.com/advisories/vtiger-crm-authenticated-file-upload-rce-via-documents-module"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
"type": "CVSS_V3"
},
{
"score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X",
"type": "CVSS_V4"
}
]
}
GHSA-3CVP-FW5M-7W6R
Vulnerability from github – Published: 2026-02-11 06:30 – Updated: 2026-02-11 06:30The Migration, Backup, Staging – WPvivid Backup & Migration plugin for WordPress is vulnerable to Unauthenticated Arbitrary File Upload in versions up to and including 0.9.123. This is due to improper error handling in the RSA decryption process combined with a lack of path sanitization when writing uploaded files. When the plugin fails to decrypt a session key using openssl_private_decrypt(), it does not terminate execution and instead passes the boolean false value to the phpseclib library's AES cipher initialization. The library treats this false value as a string of null bytes, allowing an attacker to encrypt a malicious payload using a predictable null-byte key. Additionally, the plugin accepts filenames from the decrypted payload without sanitization, enabling directory traversal to escape the protected backup directory. This makes it possible for unauthenticated attackers to upload arbitrary PHP files to publicly accessible directories and achieve Remote Code Execution via the wpvivid_action=send_to_site parameter.
{
"affected": [],
"aliases": [
"CVE-2026-1357"
],
"database_specific": {
"cwe_ids": [
"CWE-434"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-02-11T06:15:51Z",
"severity": "CRITICAL"
},
"details": "The Migration, Backup, Staging \u2013 WPvivid Backup \u0026 Migration plugin for WordPress is vulnerable to Unauthenticated Arbitrary File Upload in versions up to and including 0.9.123. This is due to improper error handling in the RSA decryption process combined with a lack of path sanitization when writing uploaded files. When the plugin fails to decrypt a session key using openssl_private_decrypt(), it does not terminate execution and instead passes the boolean false value to the phpseclib library\u0027s AES cipher initialization. The library treats this false value as a string of null bytes, allowing an attacker to encrypt a malicious payload using a predictable null-byte key. Additionally, the plugin accepts filenames from the decrypted payload without sanitization, enabling directory traversal to escape the protected backup directory. This makes it possible for unauthenticated attackers to upload arbitrary PHP files to publicly accessible directories and achieve Remote Code Execution via the wpvivid_action=send_to_site parameter.",
"id": "GHSA-3cvp-fw5m-7w6r",
"modified": "2026-02-11T06:30:41Z",
"published": "2026-02-11T06:30:41Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-1357"
},
{
"type": "WEB",
"url": "https://plugins.trac.wordpress.org/browser/wpvivid-backuprestore/tags/0.9.122/includes/class-wpvivid-crypt.php#L58"
},
{
"type": "WEB",
"url": "https://plugins.trac.wordpress.org/browser/wpvivid-backuprestore/tags/0.9.122/includes/customclass/class-wpvivid-send-to-site.php#L629"
},
{
"type": "WEB",
"url": "https://plugins.trac.wordpress.org/browser/wpvivid-backuprestore/tags/0.9.123/includes/class-wpvivid-crypt.php#L58"
},
{
"type": "WEB",
"url": "https://plugins.trac.wordpress.org/browser/wpvivid-backuprestore/tags/0.9.123/includes/customclass/class-wpvivid-send-to-site.php#L629"
},
{
"type": "WEB",
"url": "https://plugins.trac.wordpress.org/browser/wpvivid-backuprestore/trunk/includes/class-wpvivid-crypt.php#L58"
},
{
"type": "WEB",
"url": "https://plugins.trac.wordpress.org/browser/wpvivid-backuprestore/trunk/includes/customclass/class-wpvivid-send-to-site.php#L629"
},
{
"type": "WEB",
"url": "https://plugins.trac.wordpress.org/changeset/3448386/wpvivid-backuprestore#file1"
},
{
"type": "WEB",
"url": "https://www.wordfence.com/threat-intel/vulnerabilities/id/e5af0317-ef46-4744-9752-74ce228b5f37?source=cve"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
"type": "CVSS_V3"
}
]
}
GHSA-3F26-8R72-46WH
Vulnerability from github – Published: 2025-06-27 15:31 – Updated: 2026-04-01 18:35Unrestricted Upload of File with Dangerous Type vulnerability in getredhawkstudio File Manager Plugin For Wordpress allows Upload a Web Shell to a Web Server. This issue affects File Manager Plugin For Wordpress: from n/a through 7.5.
{
"affected": [],
"aliases": [
"CVE-2025-53260"
],
"database_specific": {
"cwe_ids": [
"CWE-434"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2025-06-27T14:15:45Z",
"severity": "CRITICAL"
},
"details": "Unrestricted Upload of File with Dangerous Type vulnerability in getredhawkstudio File Manager Plugin For Wordpress allows Upload a Web Shell to a Web Server. This issue affects File Manager Plugin For Wordpress: from n/a through 7.5.",
"id": "GHSA-3f26-8r72-46wh",
"modified": "2026-04-01T18:35:36Z",
"published": "2025-06-27T15:31:27Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2025-53260"
},
{
"type": "WEB",
"url": "https://patchstack.com/database/wordpress/plugin/file-manager-plugin-for-wordpress/vulnerability/wordpress-file-manager-plugin-for-wordpress-plugin-7-5-arbitrary-file-upload-vulnerability?_s_id=cve"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H",
"type": "CVSS_V3"
}
]
}
GHSA-3F4H-J993-69C6
Vulnerability from github – Published: 2023-05-18 21:30 – Updated: 2024-04-04 04:14An arbitrary file upload vulnerability in the component /admin/ThemeController.java of PerfreeBlog v3.1.2 allows attackers to execute arbitrary code via a crafted file.
{
"affected": [],
"aliases": [
"CVE-2023-30333"
],
"database_specific": {
"cwe_ids": [
"CWE-434"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2023-05-18T19:15:09Z",
"severity": "CRITICAL"
},
"details": "An arbitrary file upload vulnerability in the component /admin/ThemeController.java of PerfreeBlog v3.1.2 allows attackers to execute arbitrary code via a crafted file.",
"id": "GHSA-3f4h-j993-69c6",
"modified": "2024-04-04T04:14:31Z",
"published": "2023-05-18T21:30:20Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2023-30333"
},
{
"type": "WEB",
"url": "https://github.com/j0k1rr/some-automated-script/issues/3"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
"type": "CVSS_V3"
}
]
}
GHSA-3F53-V88V-M2R8
Vulnerability from github – Published: 2025-05-22 18:31 – Updated: 2025-05-22 18:31File upload and execute vulnerabilities in ASPECT allow PHP script injection if session administrator credentials become compromised. This issue affects ASPECT-Enterprise: through 3.08.03; NEXUS Series: through 3.08.03; MATRIX Series: through 3.08.03.
{
"affected": [],
"aliases": [
"CVE-2025-30169"
],
"database_specific": {
"cwe_ids": [
"CWE-434"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2025-05-22T18:15:41Z",
"severity": "MODERATE"
},
"details": "File upload and execute vulnerabilities in ASPECT allow PHP script injection if session administrator credentials become compromised.\nThis issue affects ASPECT-Enterprise: through 3.08.03; NEXUS Series: through 3.08.03; MATRIX Series: through 3.08.03.",
"id": "GHSA-3f53-v88v-m2r8",
"modified": "2025-05-22T18:31:16Z",
"published": "2025-05-22T18:31:16Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2025-30169"
},
{
"type": "WEB",
"url": "https://search.abb.com/library/Download.aspx?DocumentID=9AKK108471A0021\u0026LanguageCode=en\u0026DocumentPartId=pdf\u0026Action=Launch"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:L/I:H/A:H",
"type": "CVSS_V3"
},
{
"score": "CVSS:4.0/AV:N/AC:L/AT:P/PR:H/UI:N/VC:L/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:N/AU:N/R:U/V:C/RE:X/U:X",
"type": "CVSS_V4"
}
]
}
GHSA-3F75-53R3-6GHW
Vulnerability from github – Published: 2023-11-01 12:30 – Updated: 2023-11-01 12:30Lack of mime type response header in Bitrix24 22.0.300 allows authenticated remote attackers to execute arbitrary JavaScript code in the victim's browser, and possibly execute arbitrary PHP code on the server if the victim has administrator privilege, via uploading a crafted HTML file through /desktop_app/file.ajax.php?action=uploadfile.
{
"affected": [],
"aliases": [
"CVE-2023-1720"
],
"database_specific": {
"cwe_ids": [
"CWE-434"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2023-11-01T10:15:09Z",
"severity": "CRITICAL"
},
"details": "Lack of mime type response header in Bitrix24 22.0.300 allows authenticated remote attackers to execute arbitrary JavaScript code in the victim\u0027s browser, and possibly execute arbitrary PHP code on the server if the victim has administrator privilege, via uploading a crafted HTML file through /desktop_app/file.ajax.php?action=uploadfile.",
"id": "GHSA-3f75-53r3-6ghw",
"modified": "2023-11-01T12:30:19Z",
"published": "2023-11-01T12:30:19Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2023-1720"
},
{
"type": "WEB",
"url": "https://starlabs.sg/advisories/23/23-1720"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H",
"type": "CVSS_V3"
}
]
}
Mitigation
Generate a new, unique filename for an uploaded file instead of using the user-supplied filename, so that no external input is used at all.[REF-422] [REF-423]
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
Consider storing the uploaded files outside of the web document root entirely. Then, use other mechanisms to deliver the files dynamically. [REF-423]
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.
- For example, limiting filenames to alphanumeric characters can help to restrict the introduction of unintended file extensions.
Mitigation
Define a very limited set of allowable extensions and only generate filenames that end in these extensions. Consider the possibility of XSS (CWE-79) before allowing .html or .htm file types.
Mitigation
Strategy: Input Validation
Ensure that only one extension is used in the filename. Some web servers, including some versions of Apache, may process files based on inner extensions so that "filename.php.gif" is fed to the PHP interpreter.[REF-422] [REF-423]
Mitigation
When running on a web server that supports case-insensitive filenames, perform case-insensitive evaluations of the extensions that are provided.
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
Do not rely exclusively on sanity checks of file contents to ensure that the file is of the expected type and size. It may be possible for an attacker to hide code in some file segments that will still be executed by the server. For example, GIF images may contain a free-form comments field.
Mitigation
Do not rely exclusively on the MIME content type or filename attribute when determining how to render a file. Validating the MIME content type and ensuring that it matches the extension is only a partial solution.
Mitigation MIT-17
Strategy: Environment Hardening
Run your code using the lowest privileges that are required to accomplish the necessary tasks [REF-76]. If possible, create isolated accounts with limited privileges that are only used for a single task. That way, a successful attack will not immediately give the attacker access to the rest of the software or its environment. For example, database applications rarely need to run as the database administrator, especially in day-to-day operations.
Mitigation MIT-22
Strategy: Sandbox or Jail
- Run the code in a "jail" or similar sandbox environment that enforces strict boundaries between the process and the operating system. This may effectively restrict which files can be accessed in a particular directory or which commands can be executed by the software.
- OS-level examples include the Unix chroot jail, AppArmor, and SELinux. In general, managed code may provide some protection. For example, java.io.FilePermission in the Java SecurityManager allows the software to specify restrictions on file operations.
- This may not be a feasible solution, and it only limits the impact to the operating system; the rest of the application may still be subject to compromise.
- Be careful to avoid CWE-243 and other weaknesses related to jails.
CAPEC-1: Accessing Functionality Not Properly Constrained by ACLs
In applications, particularly web applications, access to functionality is mitigated by an authorization framework. This framework maps Access Control Lists (ACLs) to elements of the application's functionality; particularly URL's for web apps. In the case that the administrator failed to specify an ACL for a particular element, an attacker may be able to access it with impunity. An attacker with the ability to access functionality not properly constrained by ACLs can obtain sensitive information and possibly compromise the entire application. Such an attacker can access resources that must be available only to users at a higher privilege level, can access management sections of the application, or can run queries for data that they otherwise not supposed to.