{"id":"CVE-2026-71478","title":"league/commonmark is a PHP library for parsing and rendering CommonMark Markdown","summary":"league/commonmark is a PHP library for parsing and rendering CommonMark Markdown. From 1.5.0 until 2.9.0, the AttributesExtension's href and src unsafe-link filter can be bypassed by embedding control bytes, such as a tab, carriage retur…","severity":"medium","cvss":6.1,"cvssVector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N","cwe":["CWE-79","CWE-86","CWE-692"],"vendor":"league","product":"league/commonmark","affected":["league/commonmark >= 1.5.0, <= 2.8.3"],"patched":["league/commonmark 2.9.0"],"published":"2026-08-06","updated":"2026-09-10","sourceUpdated":"2026-09-10T20:41:33.140","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-71478","references":[{"url":"https://github.com/thephpleague/commonmark/commit/493a5aa7d65754b73846006eaff9c2c4431a8e2c","label":"security-advisories@github.com"},{"url":"https://github.com/thephpleague/commonmark/releases/tag/2.9.0","label":"security-advisories@github.com"},{"url":"https://github.com/thephpleague/commonmark/security/advisories/GHSA-29pj-957v-52mc","label":"security-advisories@github.com"},{"url":"https://github.com/thephpleague/commonmark/security/advisories/GHSA-29pj-957v-52mc","label":"134c704f-9b21-4f2e-91b3-4a467353bcc0"},{"url":"https://github.com/advisories/GHSA-29pj-957v-52mc"}],"tags":["nvd","ghsa","composer"],"epss":0.00246,"epssPercentile":0.1619,"aliases":["GHSA-29pj-957v-52mc"],"ecosystem":"composer","ingestedAt":"2026-08-06T21:04:22.234Z","slug":"CVE-2026-71478","body":"## Overview\n\nleague/commonmark is a PHP library for parsing and rendering CommonMark Markdown. From 1.5.0 until 2.9.0, the AttributesExtension's href and src unsafe-link filter can be bypassed by embedding control bytes, such as a tab, carriage return, line feed, or leading C0 control character, in a javascript: URL that browsers discard before parsing the scheme, causing the browser to still execute the script even when the unsafe-link filter is enabled. This issue is fixed in 2.9.0.\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.\n\n## Package advisory (CVE-2026-71478)\n\nAffected packages:\n\n- `league/commonmark >= 1.5.0, <= 2.8.3`\n\nPatched in:\n\n- `league/commonmark 2.9.0`\n\nSource: https://github.com/advisories/GHSA-29pj-957v-52mc","depth":"sunlit","depthScore":34,"depthScoreParts":{"impact":33.6,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}