CVE-2022-35883

What it actually does

NULL pointer dereference in the cmark-gfm Markdown parser causes a crash when specially crafted input is processed, resulting in denial of service.

Why it matters to the business

Applications or services relying on cmark-gfm for parsing user-supplied Markdown can be crashed by authenticated local users, leading to temporary loss of functionality and potential operational disruption.

How an attack unfolds

An authenticated local user supplies crafted Markdown content to the vulnerable cmark-gfm library, triggering the NULL pointer dereference and crashing the process handling the input.

How to fix it

Upgrade github/cmark-gfm to the fixed commit 2300c1bd2c8226108885bf019655c4159cf26b59 or later.

How to confirm the fix worked

Confirm the installed version of cmark-gfm is at or beyond commit 2300c1bd2c8226108885bf019655c4159cf26b59; test parsing of known triggering inputs to verify no crash occurs.

Typical attack path

1. Identify a target process or service that uses the vulnerable cmark-gfm library for Markdown parsing.
2. Craft malicious Markdown input designed to trigger the NULL pointer dereference.
3. Submit the input locally as an authenticated user to cause the application to crash.

How to detect it

Review application and system logs for unexpected crashes or segmentation faults in processes using cmark-gfm; examine recent Markdown parsing activity preceding any outages.

What your security team should do

• Prioritize upgrade of all cmark-gfm instances to the fixed commit within standard change windows.
• Review dependencies to identify all downstream usages of cmark-gfm and schedule updates accordingly.
• Monitor for any new exploit code or increased EPSS scores post-publication.