CVE-2022-39246 matrix-android-sdk2 vulnerable to impersonation via forwarded Megolm sessions
Attackers can impersonate users by exploiting permissive key forwarding, allowing them to send messages appearing to come from others.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2022-39246?
CVE-2022-39246 is a high-severity authentication bypass vulnerability in matrix-org matrix-android-sdk2, published on 28 Sep 2022. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
matrix-android-sdk2 is the Matrix SDK for Android. Prior to version 1.5.1, an attacker cooperating with a malicious homeserver can construct messages appearing to have come from another person. Such messages will be marked with a grey shield on some platforms, but this may be missing in others. This attack is possible due to the key forwarding strategy implemented in the matrix-android-sdk2 that is too permissive. Starting with version 1.5.1, the default policy for accepting key forwards has been made more strict in the matrix-android-sdk2. The matrix-android-sdk2 will now only accept forwarded keys in response to previously issued requests and only from own, verified devices. The SDK now sets a `trusted` flag on the decrypted message upon decryption, based on whether the key used to decrypt the message was received from a trusted source. Clients need to ensure that messages decrypted with a key with `trusted = false` are decorated appropriately (for example, by showing a warning for such messages). As a workaroubnd, current users of the SDK can disable key forwarding in their forks using `CryptoService#enableKeyGossiping(enable: Boolean)`.
Which versions are affected by CVE-2022-39246?
2 open source packages ship an affected version, including org.matrix.android:matrix-android-sdk2. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
org.matrix.android:matrix-android-sdk2 Maven | All versions | 1.5.1 |
org.matrix.android:matrix-android-sdk2 Maven | All versions | 1.5.1 |
Products include Matrix Software Development Kit.
How do I fix CVE-2022-39246?
Upgrade org.matrix.android:matrix-android-sdk2 to 1.5.1 or later.
Upgrade, and rotate credentials and sessions that may have been exposed. More about Authentication bypass.
Is CVE-2022-39246 being exploited?
There is no known exploitation of CVE-2022-39246 in the wild and no public exploit code.
Other vulnerabilities in matrix-org matrix-android-sdk2
Sources
Also known as GHSA-2pvj-p485-cp3m.