Matrix iOS SDK vulnerable to impersonation via forwarded Megolm sessions

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.

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

未进行实体认证的密钥交换

Matrix 授权问题漏洞

Matrix是一个雄心勃勃的新生态系统，用于开放联合即时消息和 VoIP。 Matrix iOS SDK 0.23.19 版本之前存在安全漏洞，该漏洞源于 matrix-ios-sdk 实施了过于宽松的密钥转发策略

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