Description
league/commonmark versions before 2.6.0 contain polynomial time complexity vulnerabilities in Markdown parsing that allow attackers to cause denial of service. Attackers can submit carefully crafted Markdown inputs designed to trigger worst-case performance, and sending multiple requests in parallel exhausts CPU resources and PHP-FPM processes.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| thephpleague | commonmark | < 2.6.0 | 2.6.0 |
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
Debian
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian 14 | php-league-commonmark | 2.6.0-1 | — |
| Debian 13 | php-league-commonmark | 2.6.0-1 | — |
| Debian 12 | php-league-commonmark | No fix yet | — |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu Pro 24.04 LTS | php-league-commonmark | No fix yet | — |
| Ubuntu Pro 22.04 LTS | php-league-commonmark | No fix yet | — |
| Ubuntu Pro 20.04 LTS | php-league-commonmark | No fix yet | — |
Affected packages
| Ecosystem | Package | Affected | Fixed | Record |
|---|---|---|---|---|
| Packagist | league/commonmark | < 2.6.0 | 2.6.0 | GHSA-c2pc-g5qf-rfrf |
References
- GitHub Security Advisory (GHSA-c2pc-g5qf-rfrf) vendor-advisory
- VulnCheck Advisory: league/commonmark before 2.6.0 Denial of Service via Quadratic Complexity third-party-advisory