{"id":"CVE-2025-46734","aliases":["CLSA-2026-1771980771","DEBIAN-CVE-2025-46734","EUVD-2025-13411","GHSA-3527-qv2q-pfvx","UBUNTU-CVE-2025-46734","USN-8194-1"],"status":"published","title":"league/commonmark Cross-site Scripting vulnerability in Attributes extension","description":"league/commonmark is a PHP Markdown parser. A cross-site scripting (XSS) vulnerability in the Attributes extension of the league/commonmark library (versions 1.5.0 through 2.6.x) allows remote attackers to insert malicious JavaScript calls into HTML. The league/commonmark library provides configuration options such as `html_input: 'strip'` and `allow_unsafe_links: false` to mitigate cross-site scripting (XSS) attacks by stripping raw HTML and disallowing unsafe links. However, when the Attributes Extension is enabled, it introduces a way for users to inject arbitrary HTML attributes into elements via Markdown syntax using curly braces. Version 2.7.0 contains three changes to prevent this XSS attack vector: All attributes starting with `on` are considered unsafe and blocked by default; support for an explicit allowlist of allowed HTML attributes; and manually-added `href` and `src` attributes now respect the existing `allow_unsafe_links` configuration option. If upgrading is not feasible, please consider disabling the `AttributesExtension` for untrusted users and/or filtering the rendered HTML through a library like HTMLPurifier.","severity":{"version":"3.1","score":6.4,"vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N","level":"medium","assessor":"cna","from":"cve"},"epss":{"day":"2026-11-11","score":0.00384,"percentile":0.32942,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":true},"cwes":["CWE-79"],"published":"2025-05-05T19:52:59Z","modified":"2026-10-28T02:30:21Z","fixes":[{"ecosystem":"Packagist","package":"league/commonmark","fixed_in":["2.7.0"],"sources":["ghsa","osv"]},{"ecosystem":"TuxCare:Packagist","package":"league/commonmark","fixed_in":["1.6.7-p2+tuxcare"],"sources":["osv"]},{"ecosystem":"Debian:12","package":"php-league-commonmark","fixed_in":["2.3.9-1+deb12u1"],"sources":["osv"]},{"ecosystem":"Debian:13","package":"php-league-commonmark","fixed_in":["2.7.0-1"],"sources":["osv"]},{"ecosystem":"Debian:14","package":"php-league-commonmark","fixed_in":["2.7.0-1"],"sources":["osv"]},{"ecosystem":"Ubuntu:Pro:20.04:LTS","package":"php-league-commonmark","fixed_in":["1.3.1-1ubuntu2+esm1"],"sources":["osv"]},{"ecosystem":"Ubuntu:Pro:22.04:LTS","package":"php-league-commonmark","fixed_in":["1.6.7-1ubuntu0.1~esm1"],"sources":["osv"]},{"ecosystem":"Ubuntu:Pro:24.04:LTS","package":"php-league-commonmark","fixed_in":["2.4.2-2ubuntu0.1~esm1"],"sources":["osv"]}],"affected":[{"source":"ghsa","ecosystem":"Packagist","package":"league/commonmark","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"1.5.0"},{"fixed":"2.7.0"}]}]},{"source":"osv","ecosystem":"TuxCare:Packagist","package":"league/commonmark","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"1.6.7"},{"fixed":"1.6.7-p2+tuxcare"}]}],"versions":["1.6.7","1.6.7-p1+tuxcare"]},{"source":"osv","ecosystem":"Debian:12","package":"php-league-commonmark","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.3.9-1+deb12u1"}]}],"versions":["2.3.9-1"]},{"source":"osv","ecosystem":"Debian:13","package":"php-league-commonmark","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.7.0-1"}]}]},{"source":"osv","ecosystem":"Debian:14","package":"php-league-commonmark","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.7.0-1"}]}]},{"source":"osv","ecosystem":"Packagist","package":"league/commonmark","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"1.5.0"},{"fixed":"2.7.0"}]}],"versions":["1.5.0","1.5.1","1.5.2","1.5.3","1.5.4","1.5.5","1.5.6","1.5.7","1.5.8","1.6.0","1.6.1","1.6.2","1.6.3","1.6.4","1.6.5","1.6.6","1.6.7","2.0.0","2.0.0-beta1","2.0.0-beta2","2.0.0-beta3","2.0.0-rc1","2.0.0-rc2","2.0.1","2.0.2","2.0.3","2.0.4","2.1.0","2.1.1","2.1.2","2.1.3","2.2.0","2.2.1","2.2.2","2.2.3","2.2.4","2.2.5","2.3.0","2.3.1","2.3.2","2.3.3","2.3.4","2.3.5","2.3.6","2.3.7","2.3.8","2.3.9","2.4.0","2.4.1","2.4.2","2.4.3","2.4.4","2.5.0","2.5.1","2.5.2","2.5.3","2.6.0","2.6.1","2.6.2"]},{"source":"osv","ecosystem":"Ubuntu:Pro:20.04:LTS","package":"php-league-commonmark","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"1.3.1-1ubuntu2+esm1"}]}],"versions":["1.1.2-1","1.2.0-1","1.3.0-1","1.3.1-1","1.3.1-1ubuntu2"]},{"source":"osv","ecosystem":"Ubuntu:Pro:22.04:LTS","package":"php-league-commonmark","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"1.6.7-1ubuntu0.1~esm1"}]}],"versions":["1.5.7-2build1","1.6.6-1build1","1.6.7-1"]},{"source":"osv","ecosystem":"Ubuntu:Pro:24.04:LTS","package":"php-league-commonmark","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.4.2-2ubuntu0.1~esm1"}]}],"versions":["2.3.9-1","2.4.1-1","2.4.2-1","2.4.2-2"]},{"source":"osv","ecosystem":"Ubuntu:Pro:20.04:LTS","package":"php-league-commonmark","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"1.3.1-1ubuntu2+esm1"}]}],"versions":["1.1.2-1","1.2.0-1","1.3.0-1","1.3.1-1","1.3.1-1ubuntu2"],"bundled":3},{"source":"osv","ecosystem":"Ubuntu:Pro:22.04:LTS","package":"php-league-commonmark","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"1.6.7-1ubuntu0.1~esm1"}]}],"versions":["1.5.7-2build1","1.6.6-1build1","1.6.7-1"],"bundled":3},{"source":"osv","ecosystem":"Ubuntu:Pro:24.04:LTS","package":"php-league-commonmark","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.4.2-2ubuntu0.1~esm1"}]}],"versions":["2.3.9-1","2.4.1-1","2.4.2-1","2.4.2-2"],"bundled":3}],"products":[{"vendor":"thephpleague","product":"commonmark"}],"references":[{"url":"https://github.com/thephpleague/commonmark/security/advisories/GHSA-3527-qv2q-pfvx","tags":["x_refsource_CONFIRM","advisory","web","report"]},{"url":"https://github.com/thephpleague/commonmark/commit/f0d626cf05ad3e99e6db26ebcb9091b6cd1cd89b","tags":["x_refsource_MISC","fix","web","report"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2025-46734","tags":["advisory"]},{"url":"https://github.com/advisories/GHSA-3527-qv2q-pfvx"},{"url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2025/46xxx/CVE-2025-46734.json","tags":["advisory"]},{"url":"https://security-tracker.debian.org/tracker/CVE-2025-46734","tags":["advisory"]},{"url":"https://github.com/thephpleague/commonmark","tags":["package"]},{"url":"https://ubuntu.com/security/CVE-2025-46734","tags":["report"]},{"url":"https://www.cve.org/CVERecord?id=CVE-2025-46734","tags":["report"]},{"url":"https://ubuntu.com/security/notices/USN-8194-1","tags":["advisory"]},{"url":"https://ubuntu.com/security/CVE-2026-30838","tags":["report"]},{"url":"https://ubuntu.com/security/CVE-2026-33347","tags":["report"]}],"sources":{"cve":[{"id":"CVE-2025-46734","title":"league/commonmark Cross-site Scripting vulnerability in Attributes extension","description":"league/commonmark is a PHP Markdown parser. A cross-site scripting (XSS) vulnerability in the Attributes extension of the league/commonmark library (versions 1.5.0 through 2.6.x) allows remote attackers to insert malicious JavaScript calls into HTML. The league/commonmark library provides configuration options such as `html_input: 'strip'` and `allow_unsafe_links: false` to mitigate cross-site scripting (XSS) attacks by stripping raw HTML and disallowing unsafe links. However, when the Attributes Extension is enabled, it introduces a way for users to inject arbitrary HTML attributes into elements via Markdown syntax using curly braces. Version 2.7.0 contains three changes to prevent this XSS attack vector: All attributes starting with `on` are considered unsafe and blocked by default; support for an explicit allowlist of allowed HTML attributes; and manually-added `href` and `src` attributes now respect the existing `allow_unsafe_links` configuration option. If upgrading is not feasible, please consider disabling the `AttributesExtension` for untrusted users and/or filtering the rendered HTML through a library like HTMLPurifier.","status":"published","published":"2025-05-05T19:52:59.521Z","modified":"2025-05-06T13:47:03.821Z","cvss":[{"version":"3.1","score":6.4,"vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N","level":"medium","assessor":"cna"}],"cwes":["CWE-79"],"updated_at":"2026-11-02T14:32:36.385228Z"}],"euvd":[{"id":"EUVD-2025-13411","description":"league/commonmark is a PHP Markdown parser. A cross-site scripting (XSS) vulnerability in the Attributes extension of the league/commonmark library (versions 1.5.0 through 2.6.x) allows remote attackers to insert malicious JavaScript calls into HTML. The league/commonmark library provides configuration options such as `html_input: 'strip'` and `allow_unsafe_links: false` to mitigate cross-site scripting (XSS) attacks by stripping raw HTML and disallowing unsafe links. However, when the Attributes Extension is enabled, it introduces a way for users to inject arbitrary HTML attributes into elements via Markdown syntax using curly braces. Version 2.7.0 contains three changes to prevent this XSS attack vector: All attributes starting with `on` are considered unsafe and blocked by default; support for an explicit allowlist of allowed HTML attributes; and manually-added `href` and `src` attributes now respect the existing `allow_unsafe_links` configuration option. If upgrading is not feasible, please consider disabling the `AttributesExtension` for untrusted users and/or filtering the rendered HTML through a library like HTMLPurifier.","status":"published","published":"2025-05-05T19:52:59Z","modified":"2025-05-06T13:47:03Z","cvss":[{"version":"3.1","score":6.4,"vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N","level":"medium"}],"updated_at":"2026-11-02T20:32:54.858112Z"}],"ghsa":[{"id":"GHSA-3527-qv2q-pfvx","title":"league/commonmark contains a XSS vulnerability in Attributes extension","description":"### Summary\nCross-site scripting (XSS) vulnerability in the [Attributes extension](https://commonmark.thephpleague.com/extensions/attributes/) of the league/commonmark library (versions 1.5.0 through 2.6.x) allows remote attackers to insert malicious JavaScript calls into HTML.\n\n### Details\n\nThe league/commonmark library provides configuration options such as `html_input: 'strip'` and `allow_unsafe_links: false` to mitigate cross-site scripting (XSS) attacks by stripping raw HTML and disallowing unsafe links. However, when the Attributes Extension is enabled, it introduces a way for users to inject arbitrary HTML attributes into elements via Markdown syntax using curly braces.\n\nAs a result, even with the secure configuration shown above, an attacker can inject dangerous attributes into applications using this extension via a payload such as:\n\n```md\n![](){onerror=alert(1)}\n```\n\nWhich results in the following HTML:\n\n```html\n\u003cp\u003e\u003cimg onerror=\"alert(1)\" src=\"\" alt=\"\" /\u003e\u003c/p\u003e\n```\n\nWhich causes the JS to execute immediately on page load.\n\n### Patches\n\nVersion 2.7.0 contains three changes to prevent this XSS attack vector:\n\n- All attributes starting with `on` are considered unsafe and blocked by default\n- [Support for an explicit allowlist of allowed HTML attributes](https://commonmark.thephpleague.com/2.7/extensions/attributes/#configuration)\n- Manually-added `href` and `src` attributes now respect the existing `allow_unsafe_links` configuration option\n\n### Workarounds\n\nIf upgrading is not feasible, please consider:\n\n- Disabling the `AttributesExtension` for untrusted users\n- [Filtering the rendered HTML through a library like HTMLPurifier](https://commonmark.thephpleague.com/security/#additional-filtering)","status":"published","published":"2025-05-05T20:40:36Z","modified":"2026-05-28T10:01:30Z","cvss":[{"version":"3.1","score":6.4,"vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N","level":"medium"}],"cwes":["CWE-79"],"updated_at":"2026-11-02T14:40:14.666177Z"}],"nvd":[{"id":"CVE-2025-46734","description":"league/commonmark is a PHP Markdown parser. A cross-site scripting (XSS) vulnerability in the Attributes extension of the league/commonmark library (versions 1.5.0 through 2.6.x) allows remote attackers to insert malicious JavaScript calls into HTML. The league/commonmark library provides configuration options such as `html_input: 'strip'` and `allow_unsafe_links: false` to mitigate cross-site scripting (XSS) attacks by stripping raw HTML and disallowing unsafe links. However, when the Attributes Extension is enabled, it introduces a way for users to inject arbitrary HTML attributes into elements via Markdown syntax using curly braces. Version 2.7.0 contains three changes to prevent this XSS attack vector: All attributes starting with `on` are considered unsafe and blocked by default; support for an explicit allowlist of allowed HTML attributes; and manually-added `href` and `src` attributes now respect the existing `allow_unsafe_links` configuration option. If upgrading is not feasible, please consider disabling the `AttributesExtension` for untrusted users and/or filtering the rendered HTML through a library like HTMLPurifier.","status":"published","published":"2025-05-05T20:15:21.613Z","modified":"2026-06-17T09:26:53.917Z","cvss":[{"version":"3.1","score":6.4,"vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N","level":"medium","assessor":"secondary"}],"cwes":["CWE-79"],"updated_at":"2026-11-02T14:11:04.33372Z"}],"osv":[{"id":"CVE-2025-46734","title":"league/commonmark Cross-site Scripting vulnerability in Attributes extension","description":"league/commonmark is a PHP Markdown parser. A cross-site scripting (XSS) vulnerability in the Attributes extension of the league/commonmark library (versions 1.5.0 through 2.6.x) allows remote attackers to insert malicious JavaScript calls into HTML. The league/commonmark library provides configuration options such as `html_input: 'strip'` and `allow_unsafe_links: false` to mitigate cross-site scripting (XSS) attacks by stripping raw HTML and disallowing unsafe links. However, when the Attributes Extension is enabled, it introduces a way for users to inject arbitrary HTML attributes into elements via Markdown syntax using curly braces. Version 2.7.0 contains three changes to prevent this XSS attack vector: All attributes starting with `on` are considered unsafe and blocked by default; support for an explicit allowlist of allowed HTML attributes; and manually-added `href` and `src` attributes now respect the existing `allow_unsafe_links` configuration option. If upgrading is not feasible, please consider disabling the `AttributesExtension` for untrusted users and/or filtering the rendered HTML through a library like HTMLPurifier.","status":"published","published":"2025-05-05T19:52:59.521Z","modified":"2026-10-28T02:30:21.073185702Z","cvss":[{"version":"3.1","score":6.4,"vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N","level":"medium"}],"cwes":["CWE-79"],"updated_at":"2026-11-02T15:44:49.707645Z"},{"id":"DEBIAN-CVE-2025-46734","description":"league/commonmark is a PHP Markdown parser. A cross-site scripting (XSS) vulnerability in the Attributes extension of the league/commonmark library (versions 1.5.0 through 2.6.x) allows remote attackers to insert malicious JavaScript calls into HTML. The league/commonmark library provides configuration options such as `html_input: 'strip'` and `allow_unsafe_links: false` to mitigate cross-site scripting (XSS) attacks by stripping raw HTML and disallowing unsafe links. However, when the Attributes Extension is enabled, it introduces a way for users to inject arbitrary HTML attributes into elements via Markdown syntax using curly braces. Version 2.7.0 contains three changes to prevent this XSS attack vector: All attributes starting with `on` are considered unsafe and blocked by default; support for an explicit allowlist of allowed HTML attributes; and manually-added `href` and `src` attributes now respect the existing `allow_unsafe_links` configuration option. If upgrading is not feasible, please consider disabling the `AttributesExtension` for untrusted users and/or filtering the rendered HTML through a library like HTMLPurifier.","status":"published","published":"2025-05-05T20:15:21.613Z","modified":"2026-09-01T20:05:53.497956051Z","cvss":[{"version":"3.1","score":6.4,"vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N","level":"medium"}],"updated_at":"2026-11-02T15:45:47.378563Z"},{"id":"GHSA-3527-qv2q-pfvx","title":"league/commonmark contains a XSS vulnerability in Attributes extension","description":"### Summary\nCross-site scripting (XSS) vulnerability in the [Attributes extension](https://commonmark.thephpleague.com/extensions/attributes/) of the league/commonmark library (versions 1.5.0 through 2.6.x) allows remote attackers to insert malicious JavaScript calls into HTML.\n\n### Details\n\nThe league/commonmark library provides configuration options such as `html_input: 'strip'` and `allow_unsafe_links: false` to mitigate cross-site scripting (XSS) attacks by stripping raw HTML and disallowing unsafe links. However, when the Attributes Extension is enabled, it introduces a way for users to inject arbitrary HTML attributes into elements via Markdown syntax using curly braces.\n\nAs a result, even with the secure configuration shown above, an attacker can inject dangerous attributes into applications using this extension via a payload such as:\n\n```md\n![](){onerror=alert(1)}\n```\n\nWhich results in the following HTML:\n\n```html\n\u003cp\u003e\u003cimg onerror=\"alert(1)\" src=\"\" alt=\"\" /\u003e\u003c/p\u003e\n```\n\nWhich causes the JS to execute immediately on page load.\n\n### Patches\n\nVersion 2.7.0 contains three changes to prevent this XSS attack vector:\n\n- All attributes starting with `on` are considered unsafe and blocked by default\n- [Support for an explicit allowlist of allowed HTML attributes](https://commonmark.thephpleague.com/2.7/extensions/attributes/#configuration)\n- Manually-added `href` and `src` attributes now respect the existing `allow_unsafe_links` configuration option\n\n### Workarounds\n\nIf upgrading is not feasible, please consider:\n\n- Disabling the `AttributesExtension` for untrusted users\n- [Filtering the rendered HTML through a library like HTMLPurifier](https://commonmark.thephpleague.com/security/#additional-filtering)","status":"published","published":"2025-05-05T20:40:36Z","modified":"2026-03-20T21:31:21.970036Z","cvss":[{"version":"3.1","score":6.4,"vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N","level":"medium"}],"cwes":["CWE-79"],"updated_at":"2026-11-02T15:46:35.050232Z"},{"id":"UBUNTU-CVE-2025-46734","description":"league/commonmark is a PHP Markdown parser. A cross-site scripting (XSS) vulnerability in the Attributes extension of the league/commonmark library (versions 1.5.0 through 2.6.x) allows remote attackers to insert malicious JavaScript calls into HTML. The league/commonmark library provides configuration options such as `html_input: 'strip'` and `allow_unsafe_links: false` to mitigate cross-site scripting (XSS) attacks by stripping raw HTML and disallowing unsafe links. However, when the Attributes Extension is enabled, it introduces a way for users to inject arbitrary HTML attributes into elements via Markdown syntax using curly braces. Version 2.7.0 contains three changes to prevent this XSS attack vector: All attributes starting with `on` are considered unsafe and blocked by default; support for an explicit allowlist of allowed HTML attributes; and manually-added `href` and `src` attributes now respect the existing `allow_unsafe_links` configuration option. If upgrading is not feasible, please consider disabling the `AttributesExtension` for untrusted users and/or filtering the rendered HTML through a library like HTMLPurifier.","status":"published","published":"2025-05-05T20:15:00Z","modified":"2026-04-27T18:59:36.976292Z","cvss":[{"version":"3.1","score":6.4,"vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N","level":"medium"}],"updated_at":"2026-11-02T16:55:50.31802Z"},{"id":"CLSA-2026-1771980771","title":"TuxCare security update for league/commonmark (1 CVE)","description":"TuxCare rebuilt league/commonmark to address 1 CVE. Fixed in 1.6.7-p2+tuxcare.","status":"published","published":"2026-08-04T14:52:36Z","modified":"2026-10-15T09:48:04.61151404Z","updated_at":"2026-11-02T15:43:43.249928Z"},{"id":"USN-8194-1","title":"php-league-commonmark vulnerabilities","description":"It was discovered that league/commonmark did not properly restrict\nunsafe attributes when the Attributes extension was enabled. An attacker\ncould possibly use this issue to cause cross-site scripting by injecting\nmalicious code into rendered HTML. This issue only affected Ubuntu 22.04\nLTS and Ubuntu 24.04 LTS. (CVE-2025-46734)\n\nIt was discovered that league/commonmark did not properly block certain\ndisallowed HTML tags in some cases. An attacker could possibly use this\nissue to cause cross-site scripting by inserting malicious HTML that\nbypassed filtering. (CVE-2026-30838)\n\nIt was discovered that league/commonmark did not properly enforce domain\nallowlist checks in the Embed extension. An attacker could possibly use\nthis issue to bypass domain restrictions and cause untrusted content to\nbe treated as allowed. This issue only affected Ubuntu 24.04 LTS.\n(CVE-2026-33347)","status":"published","published":"2026-04-21T17:25:51Z","modified":"2026-04-27T19:14:32.92647985Z","updated_at":"2026-11-02T16:58:22.951676Z"}]}}