CVE-2021-40824 Logic error in Matrix SDK for Android
A malicious Matrix homeserver can steal room encryption keys from Element Android clients, allowing decryption of end-to-end encrypted messages.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2021-40824?
CVE-2021-40824 is a medium-severity vulnerability in n/a, published on 13 Sep 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
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.
Weakness: CWE-290
Which versions are affected by CVE-2021-40824?
2 open source packages ship an affected version, including org.matrix.android:matrix-android-sdk2. It affects 2 products.
| Package | Affected | Fixed in |
|---|---|---|
org.matrix.android:matrix-android-sdk2 Maven | All versions | 1.2.2 |
org.matrix.android:matrix-android-sdk2 Maven | All versions | 1.2.2 |
Products include Matrix Element, Matrix Matrix-Android-Sdk2.
How do I fix CVE-2021-40824?
Upgrade org.matrix.android:matrix-android-sdk2 to 1.2.2 or later.
Is CVE-2021-40824 being exploited?
There is no known exploitation of CVE-2021-40824 in the wild and no public exploit code.
Sources
Also known as CLEANSTART-2024-NV58280, GHSA-jjmc-4p83-pp26.