GHSA-h96f-fc7c-9r55
GHSA-h96f-fc7c-9r55 is a security vulnerability in tinymce. O3 Security confirms whether GHSA-h96f-fc7c-9r55 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
Regex denial of service vulnerability in codesample plugin
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.
tinymcenpmDescription
Impact
A regex denial of service (ReDoS) vulnerability was discovered in a dependency of the codesample plugin. The vulnerability allowed poorly formed ruby code samples to lock up the browser while performing syntax highlighting. This impacts users of the codesample plugin using TinyMCE 5.5.1 or lower.
Patches
This vulnerability has been patched in TinyMCE 5.6.0 by upgrading to a version of the dependency without the vulnerability.
Workarounds
To work around this vulnerability, either:
- Upgrade to TinyMCE 5.6.0 or higher
- Disable the
codesampleplugin - Disable ruby code samples using the codesample_languages setting
- Override the PrismJS syntax highlighter to version 1.21.0 or higher using the codesample_global_prismjs setting
Acknowledgements
Tiny Technologies would like to thank Erik Krogh Kristensen at GitHub for discovering this vulnerability.
References
https://www.tiny.cloud/docs/release-notes/release-notes56/#securityfixes
For more information
If you have any questions or comments about this advisory:
- Open an issue in the TinyMCE repo
- Email us at [email protected]
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | tinymce | all versions | 5.6.0 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for tinymce. 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 tinymce to 5.6.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-h96f-fc7c-9r55 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-h96f-fc7c-9r55 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-h96f-fc7c-9r55. 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-h96f-fc7c-9r55 in your dependencies?
O3 detects GHSA-h96f-fc7c-9r55 across npm dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.