CVE-2022-39257
Matrix iOS SDK vulnerable to impersonation via forwarded Megolm sessions
No known exploitation. EPSS puts it in the 55th percentile. A vendor fix is available.
What to do
The vendor has published a fix. Version details are below where the sources state them.
What it is
From the CVE record
Matrix iOS SDK allows developers to build iOS apps compatible with Matrix. Prior to version 0.23.19, 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 matrix-ios-sdk implementing a too permissive key forwarding strategy. The default policy for accepting key forwards has been made more strict in the matrix-ios-sdk version 0.23.19. matrix-ios-sdk 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). This attack requires coordination between a malicious home server and an attacker, so those who trust their home servers do not need a workaround.
In plain language
No plain-language summary for this CVE yet.
Exploitation
Where each signal puts this CVE on the scale from published to confirmed exploited.
- CISA KEV
Not in the catalog. CISA has not confirmed exploitation.
- Public exploits
No public exploit or proof of concept found in the sources we track.
- EPSS
0.8% chance of exploitation activity in the next 30 days, which ranks it in the 55th percentile of scored CVEs.
Exploit Prediction Scoring System, FIRST.org. A probability, not a confirmation.
Lifecycle
5 events over 785 days, from the signal feeds we watch.
- Patch availablerecord updated
- Publishedweakness classified, att&ck mapped
Affected products
Technical detail
CVSS 3.1 vector
Open in the CVSS calculatorCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
Scored 7.5 by NVD.
How it is reached
- Attack Vector NetworkExploitable remotely over the network without any special conditions
- Attack Complexity LowNo special conditions — the attack can be reliably reproduced
- Privileges Required NoneNo authentication required — anyone can exploit this
- User Interaction NoneNo user interaction needed — fully automated exploitation
Scope
- Scope UnchangedImpact is limited to the vulnerable component itself
Impact if exploited
- Confidentiality NoneNo confidentiality impact
- Integrity HighTotal loss of integrity — attacker can modify any data in the component
- Availability NoneNo availability impact
Weaknesses
ATT&CK techniques
Mapped from the weaknesses above (CWE to ATT&CK), not observed in attacks.
Sources
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