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.
68290 vulnerabilities reference this CWE, most recent first.
GHSA-PWXH-7358-JQ2X
Vulnerability from github – Published: 2026-08-04 20:54 – Updated: 2026-08-04 20:54Summary
Any authenticated user can store a chat message whose math block makes KaTeX fail with a stack overflow instead of a parse error. When that happens the renderer falls back to inserting the original math source into the page as HTML rather than as text, so script in the message runs in the browser of whoever views it. Every surface that renders messages is affected, including shared chats and channels, and the missing control is output escaping on the error path.
Preconditions
Default configuration, no flags involved. The attacker needs a normal user account and a way to get the target to open the content: a shared chat link, a channel the target reads, or any other message surface. No admin rights and no non-default settings are required on either side.
Impact
Script executes in the viewer's browser on the Open WebUI origin, which puts the session token in localStorage within reach and therefore allows taking over the viewing account. If the viewer is an administrator, that is administrator access to the instance. Exploitation needs the target to open the content, but nothing beyond that: no interaction with the message itself. Server-side data and availability are unaffected; the impact is entirely in the viewer's browser session.
Fix
Fixed in 0.11.0 by commit bc600d3f0 (PR #26718). The error path now HTML-escapes the math source before it reaches the DOM, so a failed render displays the formula as text instead of as markup. Upgrading fully resolves the issue; no configuration change is needed.
Root cause
Affected component: src/lib/components/chat/Messages/Markdown/KatexRenderer.svelte, the reactive block that renders math and its catch branch. Affected setup: releases 0.10.0 through 0.10.2, which are the versions carrying that fallback.
KaTeX was called with throwOnError: false, which suppresses parse errors but not a RangeError from deeply nested input. The surrounding catch treated any failure as "show the original formula" and assigned the untouched source to the value that the template inserts with {@html}. Because the Markdown math tokenizer captures everything between the delimiters verbatim, including angle brackets and complete tags, the attacker controls that string exactly.
Proof of concept
Send a chat message (or store one via any endpoint that writes message content) consisting of a single inline math block: an opening $, 100000 { characters, an <img src=x onerror=alert(document.domain)> tag, 100000 } characters, and a closing $.
python3 -c 'N=100000; print("$"+"{"*N+"<img src=x onerror=alert(document.domain)>"+"}"*N+"$")'
Open the chat as any user who can view it. KaTeX overflows the stack, the fallback inserts the raw source, and the onerror handler fires. Replacing alert() with a request carrying localStorage.token sends the viewer's session token to an attacker-controlled host; this was demonstrated against a shared chat opened by an administrator account.
Credits
@maxntv — reported the unescaped KaTeX error fallback and demonstrated session-token theft through a shared chat.
{
"affected": [
{
"package": {
"ecosystem": "PyPI",
"name": "open-webui"
},
"ranges": [
{
"events": [
{
"introduced": "0.10.0"
},
{
"fixed": "0.11.0"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [
"CVE-2026-70492"
],
"database_specific": {
"cwe_ids": [
"CWE-79"
],
"github_reviewed": true,
"github_reviewed_at": "2026-08-04T20:54:17Z",
"nvd_published_at": null,
"severity": "HIGH"
},
"details": "## Summary\nAny authenticated user can store a chat message whose math block makes KaTeX fail with a stack overflow instead of a parse error. When that happens the renderer falls back to inserting the original math source into the page as HTML rather than as text, so script in the message runs in the browser of whoever views it. Every surface that renders messages is affected, including shared chats and channels, and the missing control is output escaping on the error path.\n\n## Preconditions\nDefault configuration, no flags involved. The attacker needs a normal user account and a way to get the target to open the content: a shared chat link, a channel the target reads, or any other message surface. No admin rights and no non-default settings are required on either side.\n\n## Impact\nScript executes in the viewer\u0027s browser on the Open WebUI origin, which puts the session token in localStorage within reach and therefore allows taking over the viewing account. If the viewer is an administrator, that is administrator access to the instance. Exploitation needs the target to open the content, but nothing beyond that: no interaction with the message itself. Server-side data and availability are unaffected; the impact is entirely in the viewer\u0027s browser session.\n\n## Fix\nFixed in 0.11.0 by commit bc600d3f0 (PR #26718). The error path now HTML-escapes the math source before it reaches the DOM, so a failed render displays the formula as text instead of as markup. Upgrading fully resolves the issue; no configuration change is needed.\n\n## Root cause\nAffected component: `src/lib/components/chat/Messages/Markdown/KatexRenderer.svelte`, the reactive block that renders math and its `catch` branch. Affected setup: releases 0.10.0 through 0.10.2, which are the versions carrying that fallback.\n\nKaTeX was called with `throwOnError: false`, which suppresses parse errors but not a `RangeError` from deeply nested input. The surrounding `catch` treated any failure as \"show the original formula\" and assigned the untouched source to the value that the template inserts with `{@html}`. Because the Markdown math tokenizer captures everything between the delimiters verbatim, including angle brackets and complete tags, the attacker controls that string exactly.\n\n## Proof of concept\nSend a chat message (or store one via any endpoint that writes message content) consisting of a single inline math block: an opening `$`, 100000 `{` characters, an `\u003cimg src=x onerror=alert(document.domain)\u003e` tag, 100000 `}` characters, and a closing `$`.\n\n```\npython3 -c \u0027N=100000; print(\"$\"+\"{\"*N+\"\u003cimg src=x onerror=alert(document.domain)\u003e\"+\"}\"*N+\"$\")\u0027\n```\n\nOpen the chat as any user who can view it. KaTeX overflows the stack, the fallback inserts the raw source, and the `onerror` handler fires. Replacing `alert()` with a request carrying `localStorage.token` sends the viewer\u0027s session token to an attacker-controlled host; this was demonstrated against a shared chat opened by an administrator account.\n\n## Credits\n@maxntv \u2014 reported the unescaped KaTeX error fallback and demonstrated session-token theft through a shared chat.",
"id": "GHSA-pwxh-7358-jq2x",
"modified": "2026-08-04T20:54:17Z",
"published": "2026-08-04T20:54:17Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/open-webui/open-webui/security/advisories/GHSA-pwxh-7358-jq2x"
},
{
"type": "WEB",
"url": "https://github.com/open-webui/open-webui/pull/26718"
},
{
"type": "WEB",
"url": "https://github.com/open-webui/open-webui/commit/bc600d3f085802c45aa8f38c30e6e8c986bde6cc"
},
{
"type": "PACKAGE",
"url": "https://github.com/open-webui/open-webui"
},
{
"type": "WEB",
"url": "https://github.com/open-webui/open-webui/releases/tag/v0.11.0"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:N",
"type": "CVSS_V3"
}
],
"summary": "Open WebUI: Stored XSS via unescaped KaTeX render-error fallback in rendered messages"
}
GHSA-PWXM-8H28-3XX5
Vulnerability from github – Published: 2022-05-17 04:11 – Updated: 2022-05-17 04:11Cross-site scripting (XSS) vulnerability in the Node Field module 7.x-2.x before 7.x-2.45 for Drupal allows remote authenticated users with certain permissions to inject arbitrary web script or HTML via unspecified vectors involving internal fields.
{
"affected": [],
"aliases": [
"CVE-2014-9739"
],
"database_specific": {
"cwe_ids": [
"CWE-79"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2015-07-06T15:59:00Z",
"severity": "LOW"
},
"details": "Cross-site scripting (XSS) vulnerability in the Node Field module 7.x-2.x before 7.x-2.45 for Drupal allows remote authenticated users with certain permissions to inject arbitrary web script or HTML via unspecified vectors involving internal fields.",
"id": "GHSA-pwxm-8h28-3xx5",
"modified": "2022-05-17T04:11:59Z",
"published": "2022-05-17T04:11:59Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2014-9739"
},
{
"type": "WEB",
"url": "https://www.drupal.org/node/2373157"
},
{
"type": "WEB",
"url": "https://www.drupal.org/node/2378287"
},
{
"type": "WEB",
"url": "http://www.securityfocus.com/bid/71201"
}
],
"schema_version": "1.4.0",
"severity": []
}
GHSA-PWXR-XM9V-QFVH
Vulnerability from github – Published: 2024-09-30 06:33 – Updated: 2024-10-01 18:31The Ultimate Blocks WordPress plugin before 3.2.2 does not validate and escape some of its block attributes before outputting them back in a page/post where the block is embed, which could allow users with the contributor role and above to perform Stored Cross-Site Scripting attacks
{
"affected": [],
"aliases": [
"CVE-2024-8536"
],
"database_specific": {
"cwe_ids": [
"CWE-79"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2024-09-30T06:15:14Z",
"severity": "MODERATE"
},
"details": "The Ultimate Blocks WordPress plugin before 3.2.2 does not validate and escape some of its block attributes before outputting them back in a page/post where the block is embed, which could allow users with the contributor role and above to perform Stored Cross-Site Scripting attacks",
"id": "GHSA-pwxr-xm9v-qfvh",
"modified": "2024-10-01T18:31:17Z",
"published": "2024-09-30T06:33:37Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2024-8536"
},
{
"type": "WEB",
"url": "https://wpscan.com/vulnerability/abd5b6c6-f541-4739-882d-2011436f7a8b"
}
],
"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-PX22-JGFM-6WR7
Vulnerability from github – Published: 2023-07-06 15:30 – Updated: 2024-04-04 05:28A stored cross-site scripting (XSS) vulnerability in Bagecms v3.1.0 allows attackers to execute arbitrary web scripts or HTML via a crafted payload injected into the Custom Settings module.
{
"affected": [],
"aliases": [
"CVE-2023-37122"
],
"database_specific": {
"cwe_ids": [
"CWE-79"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2023-07-06T15:15:16Z",
"severity": "MODERATE"
},
"details": "A stored cross-site scripting (XSS) vulnerability in Bagecms v3.1.0 allows attackers to execute arbitrary web scripts or HTML via a crafted payload injected into the Custom Settings module.",
"id": "GHSA-px22-jgfm-6wr7",
"modified": "2024-04-04T05:28:13Z",
"published": "2023-07-06T15:30:35Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2023-37122"
},
{
"type": "WEB",
"url": "https://github.com/bagesoft/bagecms/issues/6"
}
],
"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-PX2G-Q8P3-HH7Q
Vulnerability from github – Published: 2025-08-20 09:30 – Updated: 2026-04-01 18:35Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') vulnerability in Jorge Garcia de Bustos AWStats Script allows Stored XSS. This issue affects AWStats Script: from n/a through 0.3.
{
"affected": [],
"aliases": [
"CVE-2025-49890"
],
"database_specific": {
"cwe_ids": [
"CWE-502",
"CWE-79"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2025-08-20T08:15:38Z",
"severity": "MODERATE"
},
"details": "Improper Neutralization of Input During Web Page Generation (\u0027Cross-site Scripting\u0027) vulnerability in Jorge Garcia de Bustos AWStats Script allows Stored XSS. This issue affects AWStats Script: from n/a through 0.3.",
"id": "GHSA-px2g-q8p3-hh7q",
"modified": "2026-04-01T18:35:54Z",
"published": "2025-08-20T09:30:40Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2025-49890"
},
{
"type": "WEB",
"url": "https://patchstack.com/database/Wordpress/Theme/organic-beauty/vulnerability/wordpress-organic-beauty-theme-1-4-6-php-object-injection-vulnerability?_s_id=cve"
},
{
"type": "WEB",
"url": "https://patchstack.com/database/wordpress/plugin/awstats-script/vulnerability/wordpress-awstats-script-plugin-0-3-cross-site-scripting-xss-vulnerability?_s_id=cve"
}
],
"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:L",
"type": "CVSS_V3"
}
]
}
GHSA-PX2R-H28W-3WX9
Vulnerability from github – Published: 2024-01-17 18:31 – Updated: 2024-01-17 18:31A vulnerability in the web-based management interface of Cisco Identity Services Engine (ISE) could allow an authenticated, remote attacker to perform a stored cross-site scripting (XSS) attack against a user of the interface on an affected device. This vulnerability exists because the web-based management interface does not properly validate user-supplied input. An attacker could exploit this vulnerability by injecting malicious code into specific pages of 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-2024-20251"
],
"database_specific": {
"cwe_ids": [
"CWE-79"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2024-01-17T17:15:11Z",
"severity": "MODERATE"
},
"details": "A vulnerability in the web-based management interface of Cisco Identity Services Engine (ISE) could allow an authenticated, remote attacker to perform a stored cross-site scripting (XSS) attack against a user of the interface on an affected device. This vulnerability exists because the web-based management interface does not properly validate user-supplied input. An attacker could exploit this vulnerability by injecting malicious code into specific pages of 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-px2r-h28w-3wx9",
"modified": "2024-01-17T18:31:38Z",
"published": "2024-01-17T18:31:38Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2024-20251"
},
{
"type": "WEB",
"url": "https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-ISE-XSS-bL4VTML"
}
],
"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-PX2R-HC96-6X9W
Vulnerability from github – Published: 2024-08-30 06:30 – Updated: 2024-08-30 06:30The Betheme theme for WordPress is vulnerable to Stored Cross-Site Scripting via several of the plugin's shortcodes in all versions up to, and including, 27.5.6 due to insufficient input sanitization and output escaping on user supplied attributes. This makes it possible for authenticated attackers, with contributor-level access and above, to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page.
{
"affected": [],
"aliases": [
"CVE-2024-3998"
],
"database_specific": {
"cwe_ids": [
"CWE-79"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2024-08-30T05:15:12Z",
"severity": "MODERATE"
},
"details": "The Betheme theme for WordPress is vulnerable to Stored Cross-Site Scripting via several of the plugin\u0027s shortcodes in all versions up to, and including, 27.5.6 due to insufficient input sanitization and output escaping on user supplied attributes. This makes it possible for authenticated attackers, with contributor-level access and above, to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page.",
"id": "GHSA-px2r-hc96-6x9w",
"modified": "2024-08-30T06:30:38Z",
"published": "2024-08-30T06:30:38Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2024-3998"
},
{
"type": "WEB",
"url": "https://themeforest.net/item/betheme-responsive-multipurpose-wordpress-theme/7758048"
},
{
"type": "WEB",
"url": "https://www.wordfence.com/threat-intel/vulnerabilities/id/5b655b04-1f2f-4745-8237-7ef3f8e31ace?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-PX2W-WV2V-R557
Vulnerability from github – Published: 2025-01-07 12:31 – Updated: 2026-04-01 18:33Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') vulnerability in Olaf Lederer EO4WP allows Stored XSS.This issue affects EO4WP: from n/a through 1.0.7.
{
"affected": [],
"aliases": [
"CVE-2025-22327"
],
"database_specific": {
"cwe_ids": [
"CWE-79"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2025-01-07T11:15:16Z",
"severity": "MODERATE"
},
"details": "Improper Neutralization of Input During Web Page Generation (\u0027Cross-site Scripting\u0027) vulnerability in Olaf Lederer EO4WP allows Stored XSS.This issue affects EO4WP: from n/a through 1.0.7.",
"id": "GHSA-px2w-wv2v-r557",
"modified": "2026-04-01T18:33:02Z",
"published": "2025-01-07T12:31:01Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2025-22327"
},
{
"type": "WEB",
"url": "https://patchstack.com/database/wordpress/plugin/fw-integration-for-emailoctopus/vulnerability/wordpress-eo4wp-plugin-1-0-7-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-PX36-5X6H-5X8G
Vulnerability from github – Published: 2021-11-20 00:00 – Updated: 2021-11-25 00:00The "WPO365 | LOGIN" WordPress plugin (up to and including version 15.3) by wpo365.com is vulnerable to a persistent Cross-Site Scripting (XSS) vulnerability (also known as Stored or Second-Order XSS). Persistent XSS vulnerabilities occur when the application stores and retrieves client supplied data without proper handling of dangerous content. This type of XSS vulnerability is exploited by submitting malicious script content to the application which is then retrieved and executed by other application users. The attacker could exploit this to conduct a range of attacks against users of the affected application such as session hijacking, account take over and accessing sensitive data. In this case, the XSS payload can be submitted by any anonymous user, the payload then renders and executes when a WordPress administrator authenticates and accesses the WordPress Dashboard. The injected payload can carry out actions on behalf of the administrator including adding other administrative users and changing application settings. This flaw could be exploited to ultimately provide full control of the affected system to the attacker.
{
"affected": [],
"aliases": [
"CVE-2021-43409"
],
"database_specific": {
"cwe_ids": [
"CWE-79"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2021-11-19T16:15:00Z",
"severity": "MODERATE"
},
"details": "The \"WPO365 | LOGIN\" WordPress plugin (up to and including version 15.3) by wpo365.com is vulnerable to a persistent Cross-Site Scripting (XSS) vulnerability (also known as Stored or Second-Order XSS). Persistent XSS vulnerabilities occur when the application stores and retrieves client supplied data without proper handling of dangerous content. This type of XSS vulnerability is exploited by submitting malicious script content to the application which is then retrieved and executed by other application users. The attacker could exploit this to conduct a range of attacks against users of the affected application such as session hijacking, account take over and accessing sensitive data. In this case, the XSS payload can be submitted by any anonymous user, the payload then renders and executes when a WordPress administrator authenticates and accesses the WordPress Dashboard. The injected payload can carry out actions on behalf of the administrator including adding other administrative users and changing application settings. This flaw could be exploited to ultimately provide full control of the affected system to the attacker.",
"id": "GHSA-px36-5x6h-5x8g",
"modified": "2021-11-25T00:00:54Z",
"published": "2021-11-20T00:00:54Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2021-43409"
},
{
"type": "WEB",
"url": "https://appcheck-ng.com/wordpress-microsoft-office-365-azure-ad-login-persistent-cross-site-scripting"
},
{
"type": "WEB",
"url": "https://www.wpo365.com/change-log"
}
],
"schema_version": "1.4.0",
"severity": []
}
GHSA-PX38-239G-X5MG
Vulnerability from github – Published: 2024-12-18 00:31 – Updated: 2024-12-18 15:38Cross-site scripting (XSS) vulnerability in the edit Service Access Policy page in Liferay Portal 7.0.0 through 7.4.3.87, and Liferay DXP 7.4 GA through update 87, 7.3 GA through update 29, and older unsupported versions allows remote attackers to inject arbitrary web script or HTML via a crafted payload injected into a service access policy's Service Class text field.
{
"affected": [
{
"package": {
"ecosystem": "Maven",
"name": "com.liferay.portal:release.portal.bom"
},
"ranges": [
{
"events": [
{
"introduced": "7.0.0"
},
{
"fixed": "7.4.3.88"
}
],
"type": "ECOSYSTEM"
}
]
},
{
"package": {
"ecosystem": "Maven",
"name": "com.liferay.portal:release.dxp.bom"
},
"ranges": [
{
"events": [
{
"introduced": "7.0"
},
{
"fixed": "7.3.10.u30"
}
],
"type": "ECOSYSTEM"
}
]
},
{
"package": {
"ecosystem": "Maven",
"name": "com.liferay.portal:release.dxp.bom"
},
"ranges": [
{
"events": [
{
"introduced": "7.4"
},
{
"fixed": "7.4.13.u88"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [
"CVE-2023-37940"
],
"database_specific": {
"cwe_ids": [
"CWE-79"
],
"github_reviewed": true,
"github_reviewed_at": "2024-12-18T15:38:29Z",
"nvd_published_at": "2024-12-17T22:15:05Z",
"severity": "MODERATE"
},
"details": "Cross-site scripting (XSS) vulnerability in the edit Service Access Policy page in Liferay Portal 7.0.0 through 7.4.3.87, and Liferay DXP 7.4 GA through update 87, 7.3 GA through update 29, and older unsupported versions allows remote attackers to inject arbitrary web script or HTML via a crafted payload injected into a service access policy\u0027s `Service Class` text field.",
"id": "GHSA-px38-239g-x5mg",
"modified": "2024-12-18T15:38:29Z",
"published": "2024-12-18T00:31:23Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2023-37940"
},
{
"type": "PACKAGE",
"url": "https://github.com/liferay/liferay-portal"
},
{
"type": "WEB",
"url": "https://liferay.dev/portal/security/known-vulnerabilities/-/asset_publisher/jekt/content/CVE-2023-37940"
}
],
"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"
}
],
"summary": "Liferay Portal and Liferay DXP have Cross-site Scripting vulnerability in edit Service Access Policy page"
}
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.