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.
Published 2022-09-28 21:15:14
Updated 2022-09-30 16:10:54
Source GitHub, Inc.
View at NVD,   CVE.org
Vulnerability category: BypassGain privilege

Exploit prediction scoring system (EPSS) score for CVE-2022-39257

0.09%
Probability of exploitation activity in the next 30 days EPSS Score History
~ 37 %
Percentile, the proportion of vulnerabilities that are scored at or less

CVSS scores for CVE-2022-39257

Base Score Base Severity CVSS Vector Exploitability Score Impact Score Score Source First Seen
7.5
HIGH CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
3.9
3.6
NIST
7.5
HIGH CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
3.9
3.6
GitHub, Inc.

CWE ids for CVE-2022-39257

  • When an actor claims to have a given identity, the product does not prove or insufficiently proves that the claim is correct.
    Assigned by:
    • nvd@nist.gov (Primary)
    • security-advisories@github.com (Secondary)
  • The product performs a key exchange with an actor without verifying the identity of that actor.
    Assigned by: security-advisories@github.com (Secondary)

References for CVE-2022-39257

Products affected by CVE-2022-39257

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