CVE-2024-42369: Matrix JavaScript SDK

Medium severity, CVSS 5.3. EPSS: 0.5% chance of exploitation in the next 30 days.

matrix-js-sdk is a Matrix messaging protocol Client-Server SDK for JavaScript. 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. This was patched in matrix-js-sdk 34.3.1.

Affected products

• Matrix JavaScript SDK: before 34.3.1 (fixed in 34.3.1)

Published 2024-08-20. Last modified 2026-06-17.