CVE-2023-22486 cmark-gfm Quadratic complexity bug in handle_close_bracket may lead to a denial of service

Low 3.5 Published 24 Jan 2023 Updated 10 Mar 2025

An attacker can cause denial of service in cmark-gfm by triggering quadratic complexity in bracket handling, exhausting resources.

Exploited in the wild: Not known
Login needed: Any signed-in user
Attackable: Local or same network only
Victim action needed: Not needed
Fix: Available

What is CVE-2023-22486?

CVE-2023-22486 is a low-severity denial of service vulnerability in github cmark-gfm, published on 24 Jan 2023. It can only be exploited from the same machine or local network, with no action from the victim.

Official description

cmark-gfm is GitHub's fork of cmark, a CommonMark parsing and rendering library and program in C. Versions prior to 0.29.0.gfm.7 contain a polynomial time complexity issue in handle_close_bracket that may lead to unbounded resource exhaustion and subsequent denial of service. This vulnerability has been patched in 0.29.0.gfm.7.

Weakness: CWE-407, CWE-400

Which versions are affected by CVE-2023-22486?

It affects 1 product.

Linux distribution packages (3)

`cmark` SUSE:Linux Enterprise Module for Development Tools 15 SP4	All versions	`0.30.2-150400.3.3.1`
`cmark` SUSE:Linux Enterprise Module for Package Hub 15 SP4	All versions	`0.30.2-150400.3.3.1`
`cmark` openSUSE:Leap 15.4	All versions	`0.30.2-150400.3.3.1`

Products include Github Cmark-Gfm.

How do I fix CVE-2023-22486?

Upgrade to a fixed version.

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-2023-22486 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2023-22486 exists.

Sources

Also known as CLEANSTART-2024-CU29214, DEBIAN-CVE-2023-22486, GHSA-r572-jvj2-3m8p, SUSE-SU-2023:1834-1, UBUNTU-CVE-2023-22486.