Vulnerability in Matrix Element
CVE-2021-40824
A logic error in the room key sharing functionality of Element Android before 1.2.2 and matrix-android-sdk2 (aka Matrix SDK for Android) before 1.2.2 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 attacker to decrypt end-to-end encrypted messages sent by affected clients.
Published · last modified .
CVSS v3 metric
CVSS v3 base score 5.9 (Medium). Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N.
EPSS exploit prediction
EPSS: 0.007 (49.7th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 50th percentile — 49.7% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.007 · newest: 0.007 · change: 0.000
Affected products
Weakness classification (CWE)
References
- matrix.org/blog/2021/09/13/vulnerability-disclosure-key-sharing (Vendor Advisory)
- github.com/matrix-org/matrix-android-sdk2/releases/tag/v1.2.2 (Patch, Third Party Advisory)
Frequently asked questions
- What is CVE-2021-40824?
- CVE-2021-40824 is a medium-severity vulnerability in Matrix Element, classified under Authentication Bypass by Spoofing. CVSS score: 5.9/10. Published 2021-09-13.
- How severe is CVE-2021-40824?
- Medium severity. CVSS v3 base score is 5.9 out of 10.