GHSA-62q6-4hv4-vjrw
CRITICALGHSA-62q6-4hv4-vjrw is a critical-severity (CVSS 9.6) CWE-524 vulnerability in ghost. O3 Security confirms whether GHSA-62q6-4hv4-vjrw is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
Ghost: Cache-poisoning XSS in Ghost frontend via x-ghost-preview header
Real-World Exposure
How broadly this vulnerability is actually deployed: weekly install volume shows current usage, a proxy for how much of the ecosystem is exposed.
ghostnpmDescription
Impact
When Ghost is behind a shared caching layer that results in cached content being shared between different visitors (e.g., Fastly, Cloudflare, nginx proxy_cache, and others), an unauthenticated user could send an x-ghost-preview header that altered the rendered frontend response. In affected cache configurations, that response could be stored and served to subsequent visitors requesting the same page, allowing cache poisoning of request-specific preview output.
When running Ghost's frontend and admin panel on the same domain this could be used to take over staff user accounts. When running these on different domains staff accounts have no exposure.
Vulnerable versions
This vulnerability is present in Ghost from v4.0 up to v6.36.0.
Patches
v6.37.0 contains a fix for this issue.
How to update
For self-hosters using Docker, find Docker's official Ghost image here. Updating a Docker-based Ghost instance is documented here.
If your Ghost is a Ghost-CLI install see our documentation on updating it to the latest version here.
If you suspect a credential compromise, use the “Reset all authentication” dialogue under Settings / Danger Zone. This is available starting with Ghost v6.41.0.
Workarounds
At the caching layer, bypass the cache for x-ghost-preview requests.
References
Ghost thanks CryptoCat for disclosing this vulnerability responsibly.
For more information
If you have any questions or comments about this advisory, email us at [email protected].
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | ghost | ≥ 4.0.0&&< 6.37.0 | 6.37.0 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for ghost. 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 ghost to 6.37.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-62q6-4hv4-vjrw 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-62q6-4hv4-vjrw 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-62q6-4hv4-vjrw. 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-62q6-4hv4-vjrw in your dependencies?
O3 detects GHSA-62q6-4hv4-vjrw across npm dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.