matrix-js-sdk will freeze when a user sets a room with itself as a its predecessor

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS 4.0

5.1 · CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:P/VC:N/VI:N/VA:L/SC:N/SI:N/SA:L · score source

EPSS

• CVE-2024-42369: 0.48% estimated exploitation activity in the next 30 days; percentile 41.64 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

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.

Published by the source

20 Aug 2024, 18:35 UTC

Last modified by the source

20 Aug 2024, 18:58 UTC

Source last checked

26 Oct 2026, 12:31 UTC

1. Revision 3 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-vhr5-g3pm-49fm

2. Revision 2 · amended · 25 Oct 2026

   Reviewed OSV alias/range/CVSS4 correction; package source scopes and original publication preserved. No customer finding resolved.

3. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-vhr5-g3pm-49fm

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# Patch Next advisory brief: CVE-2024-42369

Advisory: matrix-js-sdk will freeze when a user sets a room with itself as a its predecessor
IDs: CVE-2024-42369, GHSA-vhr5-g3pm-49fm
Record: https://patchnext.com/advisories/cve-2024-42369 (revision 3, source checked 26 Oct 2026, 12:31 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 5.1)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: matrix-js-sdk 34.3.1. A vendor fix does not mean a deployment is fixed.

## Affected components
- npm matrix-js-sdk: affected < 34.3.1; fixed in 34.3.1

## Suggested inspection (read-only)
- `npm ls matrix-js-sdk --all`: lists every installed copy and version, including transitive ones. Run in the project root after `npm ci`.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on matrix-js-sdk.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://osv.dev/vulnerability/GHSA-vhr5-g3pm-49fm (OSV record GHSA-vhr5-g3pm-49fm lists affected ranges: npm matrix-js-sdk >=0 <34.3.1 (fixed))
- Verified: https://github.com/advisories/GHSA-vhr5-g3pm-49fm (GitHub-reviewed advisory GHSA-vhr5-g3pm-49fm lists affected ranges: npm matrix-js-sdk >=0 <34.3.1)

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