CVE-2026-105830 league/commonmark 2.0.0 before 2.10.2 Quadratic DoS via TableStartParser
Unauthenticated attackers can cause CPU exhaustion and denial of service in league/commonmark by submitting crafted Markdown input.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-105830?
CVE-2026-105830 is a high-severity denial of service vulnerability in thephpleague commonmark, published on 8 Oct 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
league/commonmark from 2.0.0 before 2.10.2 contains a quadratic-time denial of service vulnerability in the GitHub Flavored Markdown Table extension's TableStartParser::tryStart() block-start scan. Unauthenticated attackers can submit a large paragraph of pipe-free lines not starting with letters, forcing repeated full-buffer strpos scans that exhaust PHP worker CPU.
Weakness: CWE-400
Which versions are affected by CVE-2026-105830?
2 open source packages ship an affected version, including league/commonmark.
| Package | Affected | Fixed in |
|---|---|---|
league/commonmark Packagist | From 2.0.0 | 2.10.2 |
league/commonmark Packagist | From 2.0.0 | 2.10.2 |
How do I fix CVE-2026-105830?
Upgrade league/commonmark to 2.10.2 or later.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2026-105830 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-105830 exists.
Sources
Also known as DEBIAN-CVE-2026-105830, GHSA-3q6v-r5mr-hxv8, GHSA-84wr-wccg-f5hp, UBUNTU-CVE-2026-105830.