CVE-2026-71478: thephpleague commonmark · Cross-site Scripting
Affects thephpleague commonmarkSource CVE Database V5
Not known to be exploited · CVSS 6.1 Medium : upgrade to 2.9.0 when convenient.
Data as of 5 Nov 2026, 00:01 UTC
- EPSS
- 0.3% chance of exploitation in 30 days – higher than 29% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
- Patch
- Available – fixed in 2.9.0
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:NExploitation evidence
Disclosed: evidence found.
CVE published 6 Aug 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 5 Nov 2026.
What to do
Upgrade thephpleague/commonmark to 2.9.0.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| thephpleaguecommonmark | Affected
| Fixed in– |
Packagistthephpleague/commonmarkpkg:composer/thephpleague/commonmarkOther threats | Affected
| Fixed in
|
Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.
AI-suggested
Upgrade to version 2.9.0 or later of the league/commonmark library, where this vulnerability is fixed. No other official remediation or temporary fixes are documented. Patch status is confirmed by the version fix information.
Description
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.