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CVE-2026-71478: 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

mediumCVSS 6.1CVE-2026-71478
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 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.

Details

Source
NVD Recent CVEs (US · database · site)
Severity
medium — CVSS 6.1
Published
2026-08-06
Last updated
2026-08-06
Exploitation
Not in CISA KEV at last sync

Original advisory: https://nvd.nist.gov/vuln/detail/CVE-2026-71478

Referenced CVEs

CVECSIRTS overviewExternal
CVE-2026-71478coverage & exploitation statusNVD · CVE.org

Same CVEs, other sources

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