Description
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.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| thephpleague | commonmark | 0.6.0 – < 2.9.1 | 2.9.1 |
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 | 2.10.0-1 | — |
| Debian 13 | php-league-commonmark | No fix yet | — |
| Debian 12 | php-league-commonmark | No fix yet | — |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 26.04 LTS | php-league-commonmark | No fix yet | — |
Show 3 more (older releases, extended support, other products)Fewer releases
| 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 | >= 0.6.0, < 2.9.1 | 2.9.1 | GHSA-j8pm-gj4c-rq4x |
References
- GitHub Security Advisory (GHSA-j8pm-gj4c-rq4x) vendor-advisory
- VulnCheck Advisory: league/commonmark before 2.9.1 Denial of Service via parsing third-party-advisory