How severe is GHSA-wx77-rp39-c6vg?

No CVSS score has been assigned to GHSA-wx77-rp39-c6vg yet. Review the advisory details and affected package list to assess your exposure.

Which packages are affected by GHSA-wx77-rp39-c6vg?

GHSA-wx77-rp39-c6vg affects the following packages: markdown (npm). Ecosystems affected: npm.

How do I fix GHSA-wx77-rp39-c6vg?

No patched version of markdown has shipped for GHSA-wx77-rp39-c6vg yet. Where your build allows, override or pin the dependency away from the vulnerable range, and apply any maintainer-recommended mitigation.

How do I detect GHSA-wx77-rp39-c6vg in my npm dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for markdown, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

How do I mitigate GHSA-wx77-rp39-c6vg if there is no patch (or I can't update yet)?

Cap what an attacker can consume: apply request size, rate and timeout limits in front of the affected component, and run it with memory and CPU limits so exhaustion degrades one worker rather than the whole service.

Is GHSA-wx77-rp39-c6vg actively exploited in the wild?

No public exploit code has been indexed for GHSA-wx77-rp39-c6vg 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-wx77-rp39-c6vg published, and has it been updated?

GHSA-wx77-rp39-c6vg was published on September 4, 2020 and was last updated on September 10, 2026. 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

Regular Expression Denial of Service in markdownGHSA-wx77-rp39-c6vg

GHSA-wx77-rp39-c6vg is a security vulnerability in markdown. No vendor fix is recorded yet; mitigation options are listed below.

Published

Sep 4, 2020

Updated

Sep 10, 2026

Affected

1 pkg

Patched

None yet

Exploits

None indexed

Exploitation data as of Sep 10, 2026 · OSV.dev, FIRST.org (EPSS)

Real-World Exposure

1 pkg affected

How broadly this vulnerability is actually deployed: weekly install volume shows current usage, and reverse-dependency count shows how many other packages break if it stays unpatched.

570other npm packages depend on this — each one inherits the vulnerability until it's patched upstream

markdownnpm

127Kdownloads / week

Description

All versions of markdown are vulnerable to Regular Expression Denial of Service (ReDoS). The markdown.toHTML() function has significantly degraded performance when parsing long strings containing underscores. This may lead to Denial of Service if the parser accepts user input.

Recommendation

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

Affected Packages

1 total

Ecosystem	Package	Vulnerable range	Fix
📦npm	`markdown`	≥ 0.0.0	No fix

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for markdown, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Remediation status
No patched version of markdown has shipped for GHSA-wx77-rp39-c6vg yet. Where your build allows, override or pin the dependency away from the vulnerable range, and apply any maintainer-recommended mitigation.
Mitigate without a patch
Cap what an attacker can consume: apply request size, rate and timeout limits in front of the affected component, and run it with memory and CPU limits so exhaustion degrades one worker rather than the whole service.

Frequently Asked Questions

All versions of `markdown` are vulnerable to Regular Expression Denial of Service (ReDoS). The `markdown.toHTML()` function has significantly degraded performance when parsing long strings containing underscores. This may lead to Denial of Service if the parser accepts user input. ## Recommendation No fix is currently available. Consider using an alternative package until a fix is made available.

O3 Security · Impact-Aware SCA

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