cve.bz

CVE-2021-40823

5.9 mediumEPSS 0.7%

Medium (5.9) in matrix javascript sdk. EPSS 0.7% chance of exploitation in the next 30 days. Fixed in matrix-js-sdk 12.4.1.

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.

Severity

CVSS 3.1

5.9 medium
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N
EPSS
0.7% chance of exploitation in the next 30 days; higher than 51% of CVEs (scores of 2026-10-31)
CWE
CWE-290
Published
Modified
Record from
the NVD, synced

Affected

Packages (OSV)

AdvisoryEcosystemPackageAffectedFixed in
GHSA-23cm-x6j7-6hq3npmmatrix-js-sdk<12.4.112.4.1

References

Check your stackJSON