CVE-2023-37463 Quadratic complexity bugs may lead to a denial of service

Medium 6.4 Published 13 Jul 2023 Updated 30 Oct 2024

Attackers can cause denial of service in applications using cmark-gfm by triggering quadratic complexity bugs during Markdown parsing.

Exploited in the wild: Not known
Login needed: Any signed-in user
Attackable: Over the internet
Victim action needed: Not needed
Fix: Available

What is CVE-2023-37463?

CVE-2023-37463 is a medium-severity denial of service vulnerability in github cmark-gfm, published on 13 Jul 2023. Any signed-in user can exploit it over the network, with no action from the victim.

Official description

cmark-gfm is an extended version of the C reference implementation of CommonMark, a rationalized version of Markdown syntax with a spec. Three polynomial time complexity issues in cmark-gfm may lead to unbounded resource exhaustion and subsequent denial of service. These vulnerabilities have been patched in 0.29.0.gfm.12.

Weakness: CWE-400

Which versions are affected by CVE-2023-37463?

It affects 1 product.

Linux distribution packages (1)

python-cmarkgfm openSUSE:Tumbleweed All versions 2025.10.22-1.4

Products include Github Cmark-Gfm.

How do I fix CVE-2023-37463?

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-2023-37463 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2023-37463 exists.

Sources

Also known as DEBIAN-CVE-2023-37463, GHSA-w4qg-3vf7-m9x5, openSUSE-SU-2024:13136-1, openSUSE-SU-2026:12003-1.