GHSA-4jf8-g8wp-cx7c — matrix-js-sdk
Fix: matrix-org/matrix-spec-proposals#3061GHSA-4jf8-g8wp-cx7c is a Information Exposure vulnerability in matrix-js-sdk. A fix is available for matrix-js-sdk — see the affected versions and patch details below.
Matrix JavaScript SDK's key history sharing could share keys to malicious devices
Exploitation Status
No confirmed exploitation observed yet
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for GHSA-4jf8-g8wp-cx7c.
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
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.
matrix-js-sdknpmDescription
Impact
In matrix-js-sdk versions 9.11.0 through 34.7.0, the method MatrixClient.sendSharedHistoryKeys is vulnerable to interception by malicious homeservers. The method implements functionality proposed in MSC3061 and can be used by clients to share historical message keys with newly invited users, granting them access to past messages in the room.
However, it unconditionally sends these "shared" keys to all of the invited user's devices, regardless of whether the user's cryptographic identity is verified or whether the user's devices are signed by that identity. This allows the attacker to potentially inject its own devices to receive sensitive historical keys without proper security checks.
Note that this only affects clients running the SDK with the legacy crypto stack. Clients using the new Rust cryptography stack (i.e. those that call MatrixClient.initRustCrypto() instead of MatrixClient.initCrypto()) are unaffected by this vulnerability, because MatrixClient.sendSharedHistoryKeys() raises an exception in such environments.
Patches
Fixed in matrix-js-sdk 34.8.0 by removing the vulnerable functionality.
Workarounds
Remove use of affected functionality from clients.
References
For more information
If you have any questions or comments about this advisory, please email us at security at matrix.org.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | matrix-js-sdk | ≥ 9.11.0&&< 34.8.0 | 34.8.0npm install matrix-js-sdk@34.8.0 |
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, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update matrix-js-sdk to 34.8.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-4jf8-g8wp-cx7c 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 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like GHSA-4jf8-g8wp-cx7c can be triaged on real exposure rather than presence alone.
Tailored to GHSA-4jf8-g8wp-cx7c. 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-4jf8-g8wp-cx7c in your dependencies?
O3 Security finds GHSA-4jf8-g8wp-cx7c across npm dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.