matrix-js-sdk will freeze when a user sets a room with itself as a its predecessorGHSA-vhr5-g3pm-49fm
MEDIUMFix: matrix-org/matrix-js-sdk@a0efed8GHSA-vhr5-g3pm-49fm is a medium-severity (CVSS 4.1) CWE-674 vulnerability in matrix-js-sdk. A fix is available for matrix-js-sdk — see the affected versions and patch details below.
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-vhr5-g3pm-49fm.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
Where this sits among everything scored
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
A malicious homeserver can craft a room or room structure such that the predecessors form a cycle. The matrix-js-sdk's getRoomUpgradeHistory function will infinitely recurse in this case, causing the code to hang. This method is public but also called by the 'leaveRoomChain()' method, so leaving a room will also trigger the bug.
Even if the CVSS score would be 4.1 (AV:N/AC:L/PR:L/UI:R/S:C/C:N/I:N/A:L) we classify this as High severity issue.
Patches
This was patched in matrix-js-sdk 34.3.1.
Workarounds
Sanity check rooms before passing them to the matrix-js-sdk or avoid calling either getRoomUpgradeHistory or leaveRoomChain.
References
N/A.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | matrix-js-sdk | all versions | 34.3.1npm install matrix-js-sdk@34.3.1 |
Affected Products
javascript sdkmatrixDetection & 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 34.3.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-vhr5-g3pm-49fm 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.
Frequently Asked Questions
Is GHSA-vhr5-g3pm-49fm in your dependencies?
Find it across npm, including transitive dependencies.