# CVE-2023-22485: cmark-gfm out-of-bounds read in validate_protocol

> A crafted markdown document triggers an out-of-bounds read in cmark-gfm, potentially causing a crash or denial of service.

- **Severity:** Medium 5.3 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 24 Jan 2023
- **Updated:** 10 Mar 2025
- **Also known as:** DEBIAN-CVE-2023-22485, GHSA-c944-cv5f-hpvr, UBUNTU-CVE-2023-22485

## What is CVE-2023-22485?

CVE-2023-22485 is a medium-severity vulnerability in github cmark-gfm, published on 24 Jan 2023. An attacker can exploit it over the internet without logging in, 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. In versions prior 0.29.0.gfm.7, a crafted markdown document can trigger an out-of-bounds read in the `validate_protocol` function. We believe this bug is harmless in practice, because the out-of-bounds read accesses `malloc` metadata without causing any visible damage.This vulnerability has been patched in 0.29.0.gfm.7.

Weakness: CWE-91 (XML Injection), CWE-125 (Out-of-bounds Read)

## Which versions are affected by CVE-2023-22485?

It affects 1 product.


Products: Github Cmark-Gfm.

## How do I fix CVE-2023-22485?

Upgrade to a fixed version.

## Is CVE-2023-22485 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2023-22485 exists.

## Other vulnerabilities in github cmark-gfm

- [CVE-2024-22051](https://insights.sbomify.com/CVE-2024-22051/): CommonMarker Integer Overflow Vulnerability (critical 9.8)
- [CVE-2023-37463](https://insights.sbomify.com/CVE-2023-37463/): Quadratic complexity bugs may lead to a denial of service (medium 6.4)
- [CVE-2023-24824](https://insights.sbomify.com/CVE-2023-24824/): Quadratic complexity may lead to a denial of service in cmark-gfm (medium 5.3)
- [CVE-2023-26485](https://insights.sbomify.com/CVE-2023-26485/): Quadratic complexity may lead to a denial of service in cmark-gfm (medium 5.3)
- [CVE-2023-22486](https://insights.sbomify.com/CVE-2023-22486/): cmark-gfm Quadratic complexity bug in handle_close_bracket may lead to a denial of service (low 3.5)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2023-22485 and fix it if it is affected.

What it is: CVE-2023-22485 is a medium-severity vulnerability in github cmark-gfm, published on 24 Jan 2023. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2023-22485 exists.

Affected product: github cmark-gfm. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2023-22485/ (Markdown: https://insights.sbomify.com/CVE-2023-22485/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2023-22485
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2023-22485
- OSV: https://osv.dev/vulnerability/CVE-2023-22485

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From sbomify Insights: https://insights.sbomify.com/CVE-2023-22485/
Summaries are generated and may contain mistakes; the official description above is the record.