# GHSA-x6m6-5hrf-fh6r: Denial of Service in markdown-it-toc-and-anchor

> An attacker can cause a denial of service by providing specific markdown input that triggers an infinite loop in the table of contents generator.

- **Severity:** Not scored
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 1 Sep 2020

## What is GHSA-x6m6-5hrf-fh6r?

GHSA-x6m6-5hrf-fh6r is a denial of service vulnerability in markdown-it-toc-and-anchor, published on 1 Sep 2020. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

All versions of `markdown-it-toc-and-anchor` are vulnerable to Denial of Service. Parsing markdown containing `**text**+\n@[toc]` causes the application to enter and infinite loop.

## Recommendation

No fix is currently available. Consider using an alternative module until a fix is made available.

## Which versions are affected by GHSA-x6m6-5hrf-fh6r?

2 open source packages ship an affected version, including markdown-it-toc-and-anchor.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `markdown-it-toc-and-anchor` | npm | All versions | 4.2.0 |
| `markdown-it-toc-and-anchor` | npm | All versions | 4.2.0 |

## How do I fix GHSA-x6m6-5hrf-fh6r?

Upgrade markdown-it-toc-and-anchor to 4.2.0 or later.

## Is GHSA-x6m6-5hrf-fh6r being exploited?

There is no known exploitation of GHSA-x6m6-5hrf-fh6r in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for GHSA-x6m6-5hrf-fh6r and fix it if it is affected.

What it is: GHSA-x6m6-5hrf-fh6r is a denial of service vulnerability in markdown-it-toc-and-anchor, published on 1 Sep 2020. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of GHSA-x6m6-5hrf-fh6r in the wild and no public exploit code.

Affected packages and fixed versions:
- markdown-it-toc-and-anchor (npm): affected all versions; fixed in 4.2.0
- markdown-it-toc-and-anchor (npm): affected all versions; fixed in 4.2.0

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/GHSA-x6m6-5hrf-fh6r/ (Markdown: https://insights.sbomify.com/GHSA-x6m6-5hrf-fh6r/index.md)
```

## Sources

- OSV: https://osv.dev/vulnerability/GHSA-x6m6-5hrf-fh6r

---
From sbomify Insights: https://insights.sbomify.com/GHSA-x6m6-5hrf-fh6r/
Summaries are generated and may contain mistakes; the official description above is the record.