CVE-2026-71488league/commonmark: Quadratic-time denial of service when parsing crafted Markdown
Updated under an hour ago ()
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It affects thephpleague commonmark. Add what you run to find out whether that includes you.
No exploitation reported and no EPSS estimate yet.
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Free account, 1 product
league/commonmark is a PHP library for parsing and rendering CommonMark Markdown. From 0.6.0 until 2.9.0, specially crafted Markdown lines can cause the parser to have quadratic time complexity when converting, because several parsing paths repeatedly rescan growing portions of a line to translate between character positions and byte positions, and the Autolink extension can also copy and validate the remaining line at every URL-like prefix, allowing an attacker who can submit Markdown for conversion to consume disproportionate CPU time with a comparatively small request. This issue is fixed in 2.9.0.
- CVSS
- 7.5 HIGH (v3.1, CNA)CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- Weakness (CWE)
- CWE-407, CWE-1050
- Known exploited
- Not in CISA's KEV catalog
- EPSS (exploitation in the next 30 days)
- Not loaded for this CVE
- Assigned by
- GitHub_M
- NVD analysis
- Awaiting Analysis
- Record last updated
- Aug 7, 2026
- First seen by InfoSec Signals
- Oct 9, 2026
Affected products
thephpleague commonmark thephpleague:commonmark (from the name) | from 0.6.0, < 2.9.0 | CNA record |
References
- https://github.com/thephpleague/commonmark/security/advisories/GHSA-2q4p-g7hv-5rgvx-refsource-confirm
- https://github.com/thephpleague/commonmark/commit/a6ef6cdc308dfa39a34239c35818e75892a0e6a8x-refsource-misc
- https://github.com/thephpleague/commonmark/commit/a70979ea0d7d3377bd7127536748454a922bf5ebx-refsource-misc
- https://github.com/thephpleague/commonmark/commit/c97b02e5e652b992033b93ba5d6182f706343fc6x-refsource-misc
- https://github.com/thephpleague/commonmark/releases/tag/2.9.0x-refsource-misc
The CVE record on cve.org NVD's entry
The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.