CVE-2021-40823
Description
A logic error in the room key sharing functionality of matrix-js-sdk (aka Matrix Javascript SDK) before 12.4.1 allows a malicious Matrix homeserver present in an encrypted room to steal room encryption keys (via crafted Matrix protocol messages) that were originally sent by affected Matrix clients participating in that room. This allows the homeserver to decrypt end-to-end encrypted messages sent by affected clients.
Predictions
Heuristic predictions, AS-IS, for prioritization only.
Mitigations
No mitigations published for this CVE yet.
The vendor-content worker queues fetches as references arrive (check back in a few minutes). Or — if you've already worked around this in production — publish your fix to the community-verified tier.
✚ Propose a mitigation on Community → Mitigations published via the community go through AI scoring + 2 human reviewers + 7-day silent objection window before landing here withsource_tier=community-verified.
OS impact
| OS | Version | Status | Fixed in |
|---|---|---|---|
| arch | fixed | 1.8.4-1 | |
| debian | bullseye | affected | |
Package impact
| Ecosystem | Package | Vulnerable | Fixed |
|---|---|---|---|
| npm | matrix-js-sdk | <12.4.1 | 12.4.1 |
References
- https://security.archlinux.org/ASA-202109-4
- https://security.archlinux.org/ASA-202109-5
- https://github.com/matrix-org/matrix-js-sdk/security/advisories/GHSA-23cm-x6j7-6hq3
- https://nvd.nist.gov/vuln/detail/CVE-2021-40823
- https://github.com/matrix-org/matrix-js-sdk/commit/894c24880da0e1cc81818f51c0db80e3c9fb2be9
- https://github.com/matrix-org/matrix-js-sdk
- https://github.com/matrix-org/matrix-js-sdk/releases/tag/v12.4.1
- https://matrix.org/blog/2021/09/13/vulnerability-disclosure-key-sharing
- https://security-tracker.debian.org/tracker/CVE-2021-40823
Community-verified mitigations for this CVE will appear above when contributors publish them.
Verify integrity in audit chain (admin only). AS-IS.