How severe is GHSA-x6m6-5hrf-fh6r?

GHSA-x6m6-5hrf-fh6r has a CVSS score of 7.5/10, rated HIGH. Immediate patching is strongly recommended.

Which packages are affected by GHSA-x6m6-5hrf-fh6r?

GHSA-x6m6-5hrf-fh6r affects the following packages: markdown-it-toc-and-anchor (npm). Ecosystems affected: npm.

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

Update markdown-it-toc-and-anchor to 4.2.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-x6m6-5hrf-fh6r is resolved across your whole dependency graph.

How do I detect GHSA-x6m6-5hrf-fh6r in my npm dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for markdown-it-toc-and-anchor. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.

How do I mitigate GHSA-x6m6-5hrf-fh6r if there is no patch (or I can't update yet)?

If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

How does O3 Security protect against GHSA-x6m6-5hrf-fh6r?

O3 pinpoints whether GHSA-x6m6-5hrf-fh6r is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.

Is GHSA-x6m6-5hrf-fh6r actively exploited in the wild?

No public exploit code has been indexed for GHSA-x6m6-5hrf-fh6r yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

When was GHSA-x6m6-5hrf-fh6r published, and has it been updated?

GHSA-x6m6-5hrf-fh6r was published on September 1, 2020 and was last updated on December 7, 2023. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

📦

📦 npm

Not in CISA KEV

HIGH severity

GHSA-x6m6-5hrf-fh6r

HIGH

GHSA-x6m6-5hrf-fh6r is a high-severity (CVSS 7.5) vulnerability in markdown-it-toc-and-anchor. O3 Security confirms whether GHSA-x6m6-5hrf-fh6r is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.

Denial of Service in markdown-it-toc-and-anchor

Published

Sep 1, 2020

Updated

Dec 7, 2023

Affected

1 pkg

Patched

1 / 1

Exploits

None indexed

Exploitation data as of Dec 7, 2023 · OSV.dev, FIRST.org (EPSS)

Real-World Exposure

1 pkg affected

📦markdown-it-toc-and-anchor

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects npm packages — download data is not available via public APIs for these ecosystems.

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.

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
📦npm	`markdown-it-toc-and-anchor`	all versions	4.2.0

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for markdown-it-toc-and-anchor. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update markdown-it-toc-and-anchor to 4.2.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-x6m6-5hrf-fh6r is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether GHSA-x6m6-5hrf-fh6r is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.

Tailored to GHSA-x6m6-5hrf-fh6r. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.

Frequently Asked Questions

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.

O3 Security · Impact-Aware SCA

Is GHSA-x6m6-5hrf-fh6r in your dependencies?

O3 detects GHSA-x6m6-5hrf-fh6r across npm dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.

Scan my dependencies How O3 SCA works