A logic error in the room key sharing functionality of Element Android before 1.2.2 and…
Priority LOW 28CWE-290Published · Updated
Key facts
- Attack vector
- Network
- Privileges required
- None
- User interaction
- None
- Attack complexity
- High
- Impact type
- Security bypass, Information disclosure
- Confidentiality · integrity · availability
- High · None · None
- Fix status
- Fixed
Attack profile from CVSS 3.1 · NVD. Fix status from CNA and GitHub. Impact type from CWE-290 and CWE-327.
Summary
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.
Why it matters now
EPSS 0.00662 51st percentileScored 2026-11-07
Fix Fixed org.matrix.android:matrix-android-sdk2 (Maven): 1.2.2
SSVC decision points
Not available: CISA has not published SSVC decision points for this record.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| — | — | all versions | — | No fix listed | CNA |
| — | org.matrix.android:matrix-android-sdk2 (Maven) | before 1.2.2 | 1.2.2 | Patch available | GHSA-jjmc-4p83-pp26 |
- — Vendor— Affected all versions Fixed in — No fix listed CNA
- org.matrix.android:matrix-android-sdk2 (Maven) Vendor— Affected before 1.2.2 Fixed in 1.2.2 Patch available GHSA-jjmc-4p83-pp26
CPE configurations NVD · 2
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:2.3:a:matrix:element:*:*:*:*:*:android:*:* | before 1.2.2 | Vulnerable | matrix-org |
| cpe:2.3:a:matrix:matrix-android-sdk2:*:*:*:*:*:android:*:* | before 1.2.2 | Vulnerable | matrix-org |
- cpe:2.3:a:matrix:element:*:*:*:*:*:android:*:* Versions before 1.2.2 Vulnerable ·matrix-org
- cpe:2.3:a:matrix:matrix-android-sdk2:*:*:*:*:*:android:*:* Versions before 1.2.2 Vulnerable ·matrix-org
Remediation
- Fix · GHSA-jjmc-4p83-pp26 org.matrix.android:matrix-android-sdk2 (Maven) Fixed in 1.2.2 Advisory →
Timeline
- 2026-10-02 Threatist record created from CVE-2021-40824
- 2026-10-03 Alias added: GHSA-jjmc-4p83-pp26
- 2026-10-06 EPSS moved to the 50th–90th percentile
References
More matrix-org Element vulnerabilities
- TI-2021-20136 The olm_session_describe function in Matrix libolm before 3.2.7 is vulnerable to a buffer… CVSS 3.1CRITICAL 9.8
Sources
- CVE-2021-40824 · CVE Program
- CVE-2021-40824 · NVD
- FIRST EPSS
- GHSA-jjmc-4p83-pp26 · GitHub Advisory Database · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences