CVE-2026-86430league/commonmark before 2.9.1 Denial of Service via parsing
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 versions before 2.9.1 contain multiple denial of service vulnerabilities in fenced code block detection, reference link label lookup, and emphasis delimiter processing that perform super-linear work on crafted input. Attackers can submit specially crafted Markdown with long backtick runs, nested brackets, or delimiter sequences to consume disproportionate CPU time and prevent legitimate requests from completing.
- 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
- Known exploited
- Not in CISA's KEV catalog
- EPSS (exploitation in the next 30 days)
- Not loaded for this CVE
- Assigned by
- VulnCheck
- NVD analysis
- Analyzed
- Record last updated
- Oct 8, 2026
- First seen by InfoSec Signals
- Oct 9, 2026
Affected products
thephpleague commonmark thephpleague:commonmark (from the name) | from 0.6.0 before 2.9.1; 2.9.1 not affected | CNA record |
thephpleague commonmark thephpleague:commonmark | before 2.9.1 | NVD |
References
- https://github.com/thephpleague/commonmark/security/advisories/GHSA-j8pm-gj4c-rq4xvendor-advisory
- https://www.vulncheck.com/advisories/league-commonmark-before-2.9.1-denial-of-service-via-parsingthird-party-advisory
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.