Service interruption via quadratic Markdown parsing
Published Sep 9, 2026 · Updated Sep 9, 2026
Inefficient parsing in The PHP League CommonMark before 2.6.0 allows remote attackers to interrupt service with crafted Markdown. The parser permits unbounded delimiter processing, table-cell autocompletion, URL subdomain parsing, and expanded reference-link growth on attacker-controlled lines. Reachability requires an embedding application to pass untrusted Markdown to the library; parallel requests can exhaust CPU resources or PHP-FPM workers and deny service to legitimate users.
Summary
What happened
Inefficient parsing in The PHP League CommonMark before 2.6.0 allows remote attackers to interrupt service with crafted Markdown. The parser permits unbounded delimiter processing, table-cell autocompletion, URL subdomain parsing, and expanded reference-link growth on attacker-controlled lines. Reachability requires an embedding application to pass untrusted Markdown to the library; parallel requests can exhaust CPU resources or PHP-FPM workers and deny service to legitimate users.
The record
- CVE
- CVE-2024-58382
- Published
- Sep 9, 2026
- Updated
- Sep 9, 2026
- Vendor
- The PHP League
- Product
- CommonMark
- Classifications
- CWE-407, T1499.004
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Sep 9, 2026CVE publishedPublication date reported by the CVE source.
- Sep 9, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=0 <2.6.0
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Weakness, pattern, technique
Public exploit references
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Technologies
Your stack
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Your stack
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