{"id":"CVE-2026-33347","aliases":["CLSA-2026-1776904648","DEBIAN-CVE-2026-33347","EUVD-2026-20079","GHSA-hh8v-hgvp-g3f5","UBUNTU-CVE-2026-33347","USN-8194-1"],"status":"published","title":"league/commonmark has an embed extension allowed_domains bypass","description":"league/commonmark is a PHP Markdown parser. From version 2.3.0 to before version 2.8.2, the DomainFilteringAdapter in the Embed extension is vulnerable to an allowlist bypass due to a missing hostname boundary assertion in the domain-matching regex. An attacker-controlled domain like youtube.com.evil passes the allowlist check when youtube.com is an allowed domain. This issue has been patched in version 2.8.2.","severity":{"version":"4.0","score":6.3,"vector":"CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:L/SI:L/SA:N","level":"medium","assessor":"cna","from":"cve"},"epss":{"day":"2026-11-10","score":0.00256,"percentile":0.1728,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":true},"cwes":["CWE-185","CWE-79","CWE-918"],"published":"2026-03-19T19:04:24Z","modified":"2026-10-28T02:30:56Z","fixes":[{"ecosystem":"Packagist","package":"league/commonmark","fixed_in":["2.8.2"],"sources":["ghsa","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+deb13u1"],"sources":["osv"]},{"ecosystem":"Debian:14","package":"php-league-commonmark","fixed_in":["2.8.2-1"],"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":"2.3.0"},{"last_affected":"2.8.1"},{"fixed":"2.8.2"}]}]},{"source":"osv","ecosystem":"TuxCare:Packagist","package":"league/commonmark","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"2.7.1"},{"fixed":"2.7.1-p1+tuxcare"}]}],"versions":["2.7.1"],"bundled":2},{"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+deb13u1"}]}],"versions":["2.7.0-1"]},{"source":"osv","ecosystem":"Debian:14","package":"php-league-commonmark","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.8.2-1"}]}],"versions":["2.7.0-1","2.7.1-1","2.7.1-2","2.8.0-1","2.8.1-1"]},{"source":"osv","ecosystem":"Packagist","package":"league/commonmark","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"2.3.0"},{"fixed":"2.8.2"}]}],"versions":["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","2.7.0","2.7.1","2.8.0","2.8.1"]},{"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:25.10","package":"php-league-commonmark","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["2.6.1-2","2.6.2-1","2.7.0-1"]},{"source":"osv","ecosystem":"Ubuntu:26.10","package":"php-league-commonmark","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["2.8.0-1","2.8.2-2","2.8.3-1","2.10.0-1"]},{"source":"osv","ecosystem":"Ubuntu:26.04:LTS","package":"php-league-commonmark","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["2.7.0-1","2.7.1-2","2.8.0-1"]},{"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-hh8v-hgvp-g3f5","tags":["x_refsource_CONFIRM","Mitigation","Vendor Advisory","advisory","web","report"]},{"url":"https://github.com/thephpleague/commonmark/commit/59fb075d2101740c337c7216e3f32b36c204218b","tags":["x_refsource_MISC","Patch","fix","web","report"]},{"url":"https://github.com/thephpleague/commonmark/releases/tag/2.8.2","tags":["x_refsource_MISC","Product","Release Notes","web","report"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-33347","tags":["advisory"]},{"url":"https://github.com/advisories/GHSA-hh8v-hgvp-g3f5"},{"url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/33xxx/CVE-2026-33347.json","tags":["advisory"]},{"url":"https://security-tracker.debian.org/tracker/CVE-2026-33347","tags":["advisory"]},{"url":"https://github.com/thephpleague/commonmark","tags":["package"]},{"url":"https://ubuntu.com/security/CVE-2026-33347","tags":["report"]},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-33347","tags":["report"]},{"url":"https://ubuntu.com/security/notices/USN-8194-1","tags":["advisory"]},{"url":"https://ubuntu.com/security/CVE-2025-46734","tags":["report"]},{"url":"https://ubuntu.com/security/CVE-2026-30838","tags":["report"]}],"sources":{"cve":[{"id":"CVE-2026-33347","title":"league/commonmark has an embed extension allowed_domains bypass","description":"league/commonmark is a PHP Markdown parser. From version 2.3.0 to before version 2.8.2, the DomainFilteringAdapter in the Embed extension is vulnerable to an allowlist bypass due to a missing hostname boundary assertion in the domain-matching regex. An attacker-controlled domain like youtube.com.evil passes the allowlist check when youtube.com is an allowed domain. This issue has been patched in version 2.8.2.","status":"published","published":"2026-03-24T19:26:23.872Z","modified":"2026-03-26T19:52:12.754Z","cvss":[{"version":"4.0","score":6.3,"vector":"CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:L/SI:L/SA:N","level":"medium","assessor":"cna"}],"cwes":["CWE-79","CWE-185","CWE-918"],"updated_at":"2026-11-02T14:20:07.609948Z"}],"euvd":[{"id":"EUVD-2026-20079","description":"league/commonmark is a PHP Markdown parser. From version 2.3.0 to before version 2.8.2, the DomainFilteringAdapter in the Embed extension is vulnerable to an allowlist bypass due to a missing hostname boundary assertion in the domain-matching regex. An attacker-controlled domain like youtube.com.evil passes the allowlist check when youtube.com is an allowed domain. This issue has been patched in version 2.8.2.","status":"published","published":"2026-03-24T19:26:23Z","modified":"2026-03-26T19:52:12Z","cvss":[{"version":"4.0","score":6.3,"vector":"CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:L/SI:L/SA:N","level":"medium"}],"updated_at":"2026-11-02T19:25:27.67679Z"}],"ghsa":[{"id":"GHSA-hh8v-hgvp-g3f5","title":"league/commonmark has an embed extension allowed_domains bypass","description":"### Impact\n\nThe `DomainFilteringAdapter` in the Embed extension is vulnerable to an allowlist bypass due to a missing hostname boundary assertion in the domain-matching regex. An attacker-controlled domain like `youtube.com.evil` passes the allowlist check when `youtube.com` is an allowed domain.\n\nThis enables two attack vectors:\n\n- **SSRF**: The `OscaroteroEmbedAdapter` makes server-side HTTP requests to the embed URL via the `embed/embed` library. A bypassed domain filter causes the server to make outbound requests to an attacker-controlled host, potentially probing internal services or exfiltrating request metadata.\n- **XSS**: `EmbedRenderer` outputs the oEmbed response HTML directly into the page with no sanitization. An attacker controlling the bypassed domain can return arbitrary HTML/JavaScript in their oEmbed response, which is rendered verbatim.\n\nAny application using the `Embed` extension and relying on `allowed_domains` to restrict domains when processing untrusted Markdown input is affected.\n\n### Patches\n\nThis has been patched in version **2.8.2**. The fix replaces the regex-based domain check with explicit hostname parsing using `parse_url()`, ensuring exact domain and subdomain matching only.\n\n### Workarounds\n\n- Disable the `Embed` extension, or restrict its use to trusted users\n- Provide your own domain-filtering implementation of `EmbedAdapterInterface`\n- Enable a [Content Security Policy (CSP)](https://developer.mozilla.org/en-US/docs/Web/HTTP/CSP) and outbound firewall restrictions","status":"published","published":"2026-03-19T19:04:24Z","modified":"2026-03-27T21:58:06Z","cvss":[{"version":"4.0","score":6.3,"vector":"CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:L/SI:L/SA:N","level":"medium"}],"cwes":["CWE-79","CWE-185","CWE-918"],"updated_at":"2026-11-02T14:39:44.97342Z"}],"nvd":[{"id":"CVE-2026-33347","description":"league/commonmark is a PHP Markdown parser. From version 2.3.0 to before version 2.8.2, the DomainFilteringAdapter in the Embed extension is vulnerable to an allowlist bypass due to a missing hostname boundary assertion in the domain-matching regex. An attacker-controlled domain like youtube.com.evil passes the allowlist check when youtube.com is an allowed domain. This issue has been patched in version 2.8.2.","status":"published","published":"2026-03-24T20:16:29.24Z","modified":"2026-06-17T10:37:21.27Z","cvss":[{"version":"4.0","score":6.3,"vector":"CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:L/SI:L/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","level":"medium","assessor":"secondary"},{"version":"3.1","score":6.1,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N","level":"medium","assessor":"primary"}],"cwes":["CWE-79","CWE-185","CWE-918"],"updated_at":"2026-11-02T14:12:10.568062Z"}],"osv":[{"id":"CVE-2026-33347","title":"league/commonmark has an embed extension allowed_domains bypass","description":"league/commonmark is a PHP Markdown parser. From version 2.3.0 to before version 2.8.2, the DomainFilteringAdapter in the Embed extension is vulnerable to an allowlist bypass due to a missing hostname boundary assertion in the domain-matching regex. An attacker-controlled domain like youtube.com.evil passes the allowlist check when youtube.com is an allowed domain. This issue has been patched in version 2.8.2.","status":"published","published":"2026-03-24T19:26:23.872Z","modified":"2026-10-28T02:30:56.826102707Z","cvss":[{"version":"4.0","score":6.3,"vector":"CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:L/SI:L/SA:N","level":"medium"}],"cwes":["CWE-185","CWE-79","CWE-918"],"updated_at":"2026-11-02T15:45:01.896044Z"},{"id":"DEBIAN-CVE-2026-33347","description":"league/commonmark is a PHP Markdown parser. From version 2.3.0 to before version 2.8.2, the DomainFilteringAdapter in the Embed extension is vulnerable to an allowlist bypass due to a missing hostname boundary assertion in the domain-matching regex. An attacker-controlled domain like youtube.com.evil passes the allowlist check when youtube.com is an allowed domain. This issue has been patched in version 2.8.2.","status":"published","published":"2026-03-24T20:16:29.24Z","modified":"2026-10-01T03:02:37.300460302Z","cvss":[{"version":"3.1","score":6.1,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N","level":"medium"}],"updated_at":"2026-11-02T15:45:54.587575Z"},{"id":"GHSA-hh8v-hgvp-g3f5","title":"league/commonmark has an embed extension allowed_domains bypass","description":"### Impact\n\nThe `DomainFilteringAdapter` in the Embed extension is vulnerable to an allowlist bypass due to a missing hostname boundary assertion in the domain-matching regex. An attacker-controlled domain like `youtube.com.evil` passes the allowlist check when `youtube.com` is an allowed domain.\n\nThis enables two attack vectors:\n\n- **SSRF**: The `OscaroteroEmbedAdapter` makes server-side HTTP requests to the embed URL via the `embed/embed` library. A bypassed domain filter causes the server to make outbound requests to an attacker-controlled host, potentially probing internal services or exfiltrating request metadata.\n- **XSS**: `EmbedRenderer` outputs the oEmbed response HTML directly into the page with no sanitization. An attacker controlling the bypassed domain can return arbitrary HTML/JavaScript in their oEmbed response, which is rendered verbatim.\n\nAny application using the `Embed` extension and relying on `allowed_domains` to restrict domains when processing untrusted Markdown input is affected.\n\n### Patches\n\nThis has been patched in version **2.8.2**. The fix replaces the regex-based domain check with explicit hostname parsing using `parse_url()`, ensuring exact domain and subdomain matching only.\n\n### Workarounds\n\n- Disable the `Embed` extension, or restrict its use to trusted users\n- Provide your own domain-filtering implementation of `EmbedAdapterInterface`\n- Enable a [Content Security Policy (CSP)](https://developer.mozilla.org/en-US/docs/Web/HTTP/CSP) and outbound firewall restrictions","status":"published","published":"2026-03-19T19:04:24Z","modified":"2026-03-27T22:16:23.526812Z","cvss":[{"version":"4.0","score":6.3,"vector":"CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:L/SI:L/SA:N","level":"medium"}],"cwes":["CWE-185","CWE-79","CWE-918"],"updated_at":"2026-11-02T15:46:49.28217Z"},{"id":"UBUNTU-CVE-2026-33347","description":"league/commonmark is a PHP Markdown parser. From version 2.3.0 to before version 2.8.2, the DomainFilteringAdapter in the Embed extension is vulnerable to an allowlist bypass due to a missing hostname boundary assertion in the domain-matching regex. An attacker-controlled domain like youtube.com.evil passes the allowlist check when youtube.com is an allowed domain. This issue has been patched in version 2.8.2.","status":"published","published":"2026-03-24T20:16:00Z","modified":"2026-10-17T13:00:00.944474168Z","cvss":[{"version":"4.0","score":6.3,"vector":"CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:L/SI:L/SA:N","level":"medium"},{"version":"3.1","score":6.1,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N","level":"medium"}],"updated_at":"2026-11-02T16:56:16.036833Z"},{"id":"CLSA-2026-1776904648","title":"TuxCare security update for league/commonmark (2 CVEs)","description":"TuxCare rebuilt league/commonmark to address 2 CVEs. Fixed in 2.7.1-p1+tuxcare.","status":"published","published":"2026-08-04T14:52:28Z","modified":"2026-10-15T09:47:59.573506718Z","updated_at":"2026-11-02T15:43:44.384419Z"},{"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"}]}}