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.
66759 vulnerabilities reference this CWE, most recent first.
GHSA-XC84-X7QM-X975
Vulnerability from github – Published: 2025-01-29 09:31 – Updated: 2025-01-29 09:31The Flexible Wishlist for WooCommerce – Ecommerce Wishlist & Save for later plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the ‘wishlist_name’ parameter in all versions up to, and including, 1.2.25 due to insufficient input sanitization and output escaping. This makes it possible for unauthenticated attackers to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page.
{
"affected": [],
"aliases": [
"CVE-2024-13696"
],
"database_specific": {
"cwe_ids": [
"CWE-79"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2025-01-29T08:15:19Z",
"severity": "HIGH"
},
"details": "The Flexible Wishlist for WooCommerce \u2013 Ecommerce Wishlist \u0026 Save for later plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the \u2018wishlist_name\u2019 parameter in all versions up to, and including, 1.2.25 due to insufficient input sanitization and output escaping. This makes it possible for unauthenticated attackers to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page.",
"id": "GHSA-xc84-x7qm-x975",
"modified": "2025-01-29T09:31:42Z",
"published": "2025-01-29T09:31:42Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2024-13696"
},
{
"type": "WEB",
"url": "https://plugins.trac.wordpress.org/browser/flexible-wishlist/trunk/assets/js/front.js"
},
{
"type": "WEB",
"url": "https://plugins.trac.wordpress.org/changeset/3230370"
},
{
"type": "WEB",
"url": "https://wordpress.org/plugins/flexible-wishlist/#developers"
},
{
"type": "WEB",
"url": "https://www.wordfence.com/threat-intel/vulnerabilities/id/112456a9-8bb6-4007-87da-6d0fba912498?source=cve"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:N",
"type": "CVSS_V3"
}
]
}
GHSA-XC8P-9RR6-97R2
Vulnerability from github – Published: 2026-07-07 16:51 – Updated: 2026-07-07 16:51Summary
Manually modifying chat history allows setting the html property within document metadata. This causes the frontend to enter a code path that treats document contents as HTML, and render them in an iFrame when the citation is previewed. This allows stored XSS via a weaponised document payload in a chat. The payload also executes when the citation is viewed on a shared chat.
Details
The vulnerability stems from how iFrame are implemented here:
https://github.com/open-webui/open-webui/blob/6f1486ffd0cb288d0e21f41845361924e0d742b3/src/lib/components/chat/Messages/Citations/CitationModal.svelte#L163-L170
The html attribute can be controlled by a user who manually edits the chat history. Since allow-scripts and allow-same-origin are harcoded here the sandboxing offers essentially no protection.
PoC
Create an arbitrary chat with a file upload attached:
Edit the response
Before saving, configure the browser to use an HTTP proxy tool (Burp/Caido/ZAP) and intercept the save request. Find the object within the
history and then messages objects (not the messages array) that contains the document source.
Add
html: true to metadata, update the document to an XSS payload, and forward the request.
Observe the payload is rendered in the iFrame and the javascript executes.
The payload also executes when viewed from a shared version of the chat.
Impact
Any user can create a weaponised chat that can be shared and subsequently used to target other users.
Low privilege users are at risk of having their session taken over by a payload that reads their token from local storage and exfiltrates it to an attacker controlled server.
Admins are at risk of exposing the server to RCE via same chain described in https://github.com/advisories/GHSA-w7xj-8fx7-wfch.
Caveats
The victim must expand the sources and click the document containing the payload to trigger this issue.
{
"affected": [
{
"package": {
"ecosystem": "PyPI",
"name": "open-webui"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "0.7.0"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [
"CVE-2026-26192"
],
"database_specific": {
"cwe_ids": [
"CWE-79"
],
"github_reviewed": true,
"github_reviewed_at": "2026-07-07T16:51:13Z",
"nvd_published_at": "2026-02-19T20:25:42Z",
"severity": "HIGH"
},
"details": "### Summary\nManually modifying chat history allows setting the `html` property within document metadata. This causes the frontend to enter a code path that treats document contents as HTML, and render them in an iFrame when the citation is previewed. This allows stored XSS via a weaponised document payload in a chat. The payload also executes when the citation is viewed on a shared chat.\n\n### Details\nThe vulnerability stems from how iFrame are implemented here:\nhttps://github.com/open-webui/open-webui/blob/6f1486ffd0cb288d0e21f41845361924e0d742b3/src/lib/components/chat/Messages/Citations/CitationModal.svelte#L163-L170\nThe `html` attribute can be controlled by a user who manually edits the chat history. Since `allow-scripts` and `allow-same-origin` are harcoded here the sandboxing offers essentially no protection.\n\n### PoC\nCreate an arbitrary chat with a file upload attached:\n\u003cimg width=\"2462\" height=\"1148\" alt=\"image\" src=\"https://github.com/user-attachments/assets/fad83c74-036d-41b8-bc44-87bf2a538b21\" /\u003e\nEdit the response\n\u003cimg width=\"768\" height=\"206\" alt=\"image\" src=\"https://github.com/user-attachments/assets/41a7342a-cc41-433e-8820-0bc6ed08ddd7\" /\u003e\n\u003cimg width=\"2142\" height=\"796\" alt=\"image\" src=\"https://github.com/user-attachments/assets/fb731111-e082-4172-80d1-34cff6b2a511\" /\u003e\nBefore saving, configure the browser to use an HTTP proxy tool (Burp/Caido/ZAP) and intercept the save request. Find the object within the `history` and then `messages` objects (not the `messages` array) that contains the document source.\n\u003cimg width=\"2122\" height=\"1388\" alt=\"image\" src=\"https://github.com/user-attachments/assets/1b4fbced-a6de-414d-b063-9cae44e3f449\" /\u003e\nAdd `html: true` to metadata, update the document to an XSS payload, and forward the request.\n\u003cimg width=\"2240\" height=\"1358\" alt=\"image\" src=\"https://github.com/user-attachments/assets/fd27971b-f707-458f-a14d-254f9f3ad1fa\" /\u003e\nObserve the payload is rendered in the iFrame and the javascript executes.\n\u003cimg width=\"2698\" height=\"1696\" alt=\"image\" src=\"https://github.com/user-attachments/assets/b4e31cb4-d4cc-41a9-be42-802e9b1a798d\" /\u003e\nThe payload also executes when viewed from a shared version of the chat.\n\u003cimg width=\"2742\" height=\"1258\" alt=\"image\" src=\"https://github.com/user-attachments/assets/92ee501d-8f14-4c32-8f3c-f4d3ca304ee5\" /\u003e\n\n\n### Impact\nAny user can create a weaponised chat that can be shared and subsequently used to target other users.\n\nLow privilege users are at risk of having their session taken over by a payload that reads their token from local storage and exfiltrates it to an attacker controlled server.\n\nAdmins are at risk of exposing the server to RCE via same chain described in https://github.com/advisories/GHSA-w7xj-8fx7-wfch.\n\n### Caveats\nThe victim must expand the sources and click the document containing the payload to trigger this issue.",
"id": "GHSA-xc8p-9rr6-97r2",
"modified": "2026-07-07T16:51:13Z",
"published": "2026-07-07T16:51:13Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/open-webui/open-webui/security/advisories/GHSA-xc8p-9rr6-97r2"
},
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-26192"
},
{
"type": "PACKAGE",
"url": "https://github.com/open-webui/open-webui"
},
{
"type": "WEB",
"url": "https://github.com/open-webui/open-webui/blob/6f1486ffd0cb288d0e21f41845361924e0d742b3/src/lib/components/chat/Messages/Citations/CitationModal.svelte#L163-L170"
}
],
"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": "Open WebUI vulnerable to Stored XSS via iFrame in citations model"
}
GHSA-XC8W-X6QP-W4P7
Vulnerability from github – Published: 2025-04-02 09:30 – Updated: 2025-11-03 21:33The endpoint /zabbix.php?action=export.valuemaps suffers from a Cross-Site Scripting vulnerability via the backurl parameter. This is caused by the reflection of user-supplied data without appropriate HTML escaping or output encoding. As a result, a JavaScript payload may be injected into the above endpoint causing it to be executed within the context of the victim's browser.
{
"affected": [],
"aliases": [
"CVE-2024-45699"
],
"database_specific": {
"cwe_ids": [
"CWE-79"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2025-04-02T07:15:41Z",
"severity": "HIGH"
},
"details": "The endpoint /zabbix.php?action=export.valuemaps suffers from a Cross-Site Scripting vulnerability via the backurl parameter. This is caused by the reflection of user-supplied data without appropriate HTML escaping or output encoding. As a result, a JavaScript payload may be injected into the above endpoint causing it to be executed within the context of the victim\u0027s browser.",
"id": "GHSA-xc8w-x6qp-w4p7",
"modified": "2025-11-03T21:33:28Z",
"published": "2025-04-02T09:30:33Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2024-45699"
},
{
"type": "WEB",
"url": "https://lists.debian.org/debian-lts-announce/2025/04/msg00027.html"
},
{
"type": "WEB",
"url": "https://support.zabbix.com/browse/ZBX-26254"
}
],
"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"
},
{
"score": "CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:A/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-XC98-V69G-GMM3
Vulnerability from github – Published: 2022-05-14 03:17 – Updated: 2022-05-14 03:17error.php in ILIAS 5.2.x through 5.3.x before 5.3.4 allows XSS via the text of a PDO exception.
{
"affected": [],
"aliases": [
"CVE-2018-10307"
],
"database_specific": {
"cwe_ids": [
"CWE-79"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2018-05-18T13:29:00Z",
"severity": "MODERATE"
},
"details": "error.php in ILIAS 5.2.x through 5.3.x before 5.3.4 allows XSS via the text of a PDO exception.",
"id": "GHSA-xc98-v69g-gmm3",
"modified": "2022-05-14T03:17:43Z",
"published": "2022-05-14T03:17:43Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2018-10307"
},
{
"type": "WEB",
"url": "https://github.com/ILIAS-eLearning/ILIAS/commit/ca982e59d0b76c0374c9a7fd1acf2685ca57cf41"
},
{
"type": "WEB",
"url": "https://www.ilias.de/docu/goto_docu_pg_116799_35.html"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N",
"type": "CVSS_V3"
}
]
}
GHSA-XC9C-J8FW-874P
Vulnerability from github – Published: 2022-05-14 03:32 – Updated: 2022-05-14 03:32Kentico 10 before 10.0.50 and 11 before 11.0.3 has XSS in which a crafted URL results in improper construction of a system page.
{
"affected": [],
"aliases": [
"CVE-2018-6842"
],
"database_specific": {
"cwe_ids": [
"CWE-79"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2018-03-19T14:29:00Z",
"severity": "MODERATE"
},
"details": "Kentico 10 before 10.0.50 and 11 before 11.0.3 has XSS in which a crafted URL results in improper construction of a system page.",
"id": "GHSA-xc9c-j8fw-874p",
"modified": "2022-05-14T03:32:24Z",
"published": "2022-05-14T03:32:24Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2018-6842"
},
{
"type": "WEB",
"url": "https://gist.github.com/zamous/c0afd7e21f3111de873c7bef6dcd9dd7"
}
],
"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-XC9P-WWRX-QMMV
Vulnerability from github – Published: 2024-11-11 06:30 – Updated: 2026-04-01 18:32Improper Neutralization of Input During Web Page Generation (XSS or 'Cross-site Scripting') vulnerability in Peter Shaw LH QR Codes allows Stored XSS.This issue affects LH QR Codes: from n/a through 1.06.
{
"affected": [],
"aliases": [
"CVE-2024-51572"
],
"database_specific": {
"cwe_ids": [
"CWE-79"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2024-11-11T06:15:05Z",
"severity": "MODERATE"
},
"details": "Improper Neutralization of Input During Web Page Generation (XSS or \u0027Cross-site Scripting\u0027) vulnerability in Peter Shaw LH QR Codes allows Stored XSS.This issue affects LH QR Codes: from n/a through 1.06.",
"id": "GHSA-xc9p-wwrx-qmmv",
"modified": "2026-04-01T18:32:23Z",
"published": "2024-11-11T06:30:34Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2024-51572"
},
{
"type": "WEB",
"url": "https://patchstack.com/database/Wordpress/Plugin/lh-qr-codes/vulnerability/wordpress-lh-qr-codes-plugin-1-06-stored-cross-site-scripting-xss-vulnerability?_s_id=cve"
},
{
"type": "WEB",
"url": "https://patchstack.com/database/vulnerability/lh-qr-codes/wordpress-lh-qr-codes-plugin-1-06-stored-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-XCC2-6X6R-C739
Vulnerability from github – Published: 2022-05-17 01:46 – Updated: 2022-05-17 01:46Multiple cross-site scripting (XSS) vulnerabilities in the Creative Commons module 6.x-1.x before 6.x-1.1 for Drupal allow remote authenticated users with the administer creative commons permission to inject arbitrary web script or HTML via the (1) creativecommons_user_message or (2) creativecommons_site_license_additional_text parameter.
{
"affected": [],
"aliases": [
"CVE-2012-2297"
],
"database_specific": {
"cwe_ids": [
"CWE-79"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2012-08-26T21:55:00Z",
"severity": "LOW"
},
"details": "Multiple cross-site scripting (XSS) vulnerabilities in the Creative Commons module 6.x-1.x before 6.x-1.1 for Drupal allow remote authenticated users with the administer creative commons permission to inject arbitrary web script or HTML via the (1) creativecommons_user_message or (2) creativecommons_site_license_additional_text parameter.",
"id": "GHSA-xcc2-6x6r-c739",
"modified": "2022-05-17T01:46:13Z",
"published": "2022-05-17T01:46:13Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2012-2297"
},
{
"type": "WEB",
"url": "https://exchange.xforce.ibmcloud.com/vulnerabilities/75180"
},
{
"type": "WEB",
"url": "http://drupal.org/node/1547478"
},
{
"type": "WEB",
"url": "http://drupal.org/node/1547520"
},
{
"type": "WEB",
"url": "http://secunia.com/advisories/48937"
},
{
"type": "WEB",
"url": "http://www.madirish.net/content/drupal-creative-commons-6x-10-xss-vulnerability"
},
{
"type": "WEB",
"url": "http://www.openwall.com/lists/oss-security/2012/05/03/1"
},
{
"type": "WEB",
"url": "http://www.openwall.com/lists/oss-security/2012/05/03/2"
},
{
"type": "WEB",
"url": "http://www.securityfocus.com/bid/53248"
}
],
"schema_version": "1.4.0",
"severity": []
}
GHSA-XCC7-H9W8-FH42
Vulnerability from github – Published: 2022-05-24 17:36 – Updated: 2022-10-06 00:00MediaWiki before 1.35.1 allows XSS via BlockLogFormatter.php. MediaWiki:blanknamespace potentially can be output as raw HTML with SCRIPT tags via LogFormatter::makePageLink(). This affects MediaWiki 1.33.0 and later.
{
"affected": [],
"aliases": [
"CVE-2020-35478"
],
"database_specific": {
"cwe_ids": [
"CWE-79"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2020-12-18T08:15:00Z",
"severity": "MODERATE"
},
"details": "MediaWiki before 1.35.1 allows XSS via BlockLogFormatter.php. MediaWiki:blanknamespace potentially can be output as raw HTML with SCRIPT tags via LogFormatter::makePageLink(). This affects MediaWiki 1.33.0 and later.",
"id": "GHSA-xcc7-h9w8-fh42",
"modified": "2022-10-06T00:00:55Z",
"published": "2022-05-24T17:36:55Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2020-35478"
},
{
"type": "WEB",
"url": "https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/STT5Z4A3BCXVH3WIPICWU2FP4IPIMUPC"
},
{
"type": "WEB",
"url": "https://lists.wikimedia.org/pipermail/mediawiki-announce/2020-December/000268.html"
},
{
"type": "WEB",
"url": "https://phabricator.wikimedia.org/T268938"
}
],
"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:N",
"type": "CVSS_V3"
}
]
}
GHSA-XCC9-QMCP-VMHX
Vulnerability from github – Published: 2025-01-10 18:31 – Updated: 2025-01-13 21:30Improper Neutralization of Input During Web Page Generation (XSS or 'Cross-site Scripting') vulnerability in Wikimedia Foundation Mediawiki - Breadcrumbs2 extension allows Cross-Site Scripting (XSS).This issue affects Mediawiki - Breadcrumbs2 extension: from 1.39.X before 1.39.11, from 1.41.X before 1.41.5, from 1.42.X before 1.42.4.
{
"affected": [],
"aliases": [
"CVE-2025-23078"
],
"database_specific": {
"cwe_ids": [
"CWE-79"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2025-01-10T18:15:26Z",
"severity": "MODERATE"
},
"details": "Improper Neutralization of Input During Web Page Generation (XSS or \u0027Cross-site Scripting\u0027) vulnerability in Wikimedia Foundation Mediawiki - Breadcrumbs2 extension allows Cross-Site Scripting (XSS).This issue affects Mediawiki - Breadcrumbs2 extension: from 1.39.X before 1.39.11, from 1.41.X before 1.41.5, from 1.42.X before 1.42.4.",
"id": "GHSA-xcc9-qmcp-vmhx",
"modified": "2025-01-13T21:30:52Z",
"published": "2025-01-10T18:31:41Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2025-23078"
},
{
"type": "WEB",
"url": "https://gerrit.wikimedia.org/r/q/I7878f8f7bc067080f80427b90f8d85337f172711"
},
{
"type": "WEB",
"url": "https://phabricator.wikimedia.org/T382043"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N",
"type": "CVSS_V3"
}
]
}
GHSA-XCCG-J772-65FH
Vulnerability from github – Published: 2022-05-17 05:52 – Updated: 2022-05-17 05:52Multiple cross-site scripting (XSS) vulnerabilities in Gallarific Free Edition allow remote attackers to inject arbitrary web script or HTML via (1) the e-mail address, (2) a comment, which is not properly handled during moderation, and (3) the tag parameter to gallery/tags.php.
{
"affected": [],
"aliases": [
"CVE-2008-6567"
],
"database_specific": {
"cwe_ids": [
"CWE-79"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2009-03-31T17:30:00Z",
"severity": "MODERATE"
},
"details": "Multiple cross-site scripting (XSS) vulnerabilities in Gallarific Free Edition allow remote attackers to inject arbitrary web script or HTML via (1) the e-mail address, (2) a comment, which is not properly handled during moderation, and (3) the tag parameter to gallery/tags.php.",
"id": "GHSA-xccg-j772-65fh",
"modified": "2022-05-17T05:52:46Z",
"published": "2022-05-17T05:52:46Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2008-6567"
},
{
"type": "WEB",
"url": "http://archives.neohapsis.com/archives/fulldisclosure/2008-04/0398.html"
},
{
"type": "WEB",
"url": "http://osvdb.org/51166"
},
{
"type": "WEB",
"url": "http://osvdb.org/51167"
},
{
"type": "WEB",
"url": "http://osvdb.org/51168"
},
{
"type": "WEB",
"url": "http://www.securityfocus.com/bid/28794"
}
],
"schema_version": "1.4.0",
"severity": []
}
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.