GHSA-23cm-x6j7-6hq3 is a medium-severity (CVSS 5.9) CWE-290 vulnerability in matrix-js-sdk. O3 Security confirms whether GHSA-23cm-x6j7-6hq3 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
matrix-js-sdk can be tricked into disclosing E2EE room keys to a participating homeserver
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.
matrix-js-sdknpmDescription
Impact
A logic error in the room key sharing functionality of matrix-js-sdk before 12.4.1 allows a malicious Matrix homeserver† participating in an encrypted room to steal room encryption keys from affected Matrix clients participating in that room. This allows the homeserver to decrypt end-to-end encrypted messages sent by affected clients.
† Or anyone with access to the account of the original recipient of an encrypted message.
Known clients affected (via their use of vulnerable versions of matrix-js-sdk):
- Element Web (1.8.2 and earlier)
- Element Desktop (1.8.2 and earlier)
- SchildiChat Web (1.7.32-sc1 and earlier)
- SchildiChat Desktop (1.7.32-sc1 and earlier)
- Cinny (1.2.0 and earlier)
Patch
This was fixed in https://github.com/matrix-org/matrix-js-sdk/commit/894c24880da0e1cc81818f51c0db80e3c9fb2be9.
Workarounds
To prevent a homeserver from being able to steal the room keys, vulnerable clients can be taken offline or signed out. If signing out, care should be taken to either set up Secure Backup or export E2E room keys in order to preserve access to past messages.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | matrix-js-sdk | all versions | 12.4.1 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for matrix-js-sdk. 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 matrix-js-sdk to 12.4.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-23cm-x6j7-6hq3 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-23cm-x6j7-6hq3 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-23cm-x6j7-6hq3. 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-23cm-x6j7-6hq3 in your dependencies?
O3 detects GHSA-23cm-x6j7-6hq3 across npm dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.