GHSA-h6mq-3cj6-h738 is a low-severity (CVSS 3.1) vulnerability in showdown. O3 Security confirms whether GHSA-h6mq-3cj6-h738 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
Reverse Tabnabbing in showdown
Real-World Exposure
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.
showdownnpmDescription
Versions of showdown prior to 1.9.1 are vulnerable to Reverse Tabnabbing. The package uses target='_blank' in anchor tags, allowing attackers to access window.opener for the original page when opening links. This is commonly used for phishing attacks.
Recommendation
Upgrade to version 1.9.1 or later.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | showdown | all versions | 1.9.1 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for showdown. 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 showdown to 1.9.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-h6mq-3cj6-h738 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-h6mq-3cj6-h738 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-h6mq-3cj6-h738. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is GHSA-h6mq-3cj6-h738 in your dependencies?
O3 detects GHSA-h6mq-3cj6-h738 across npm dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.