{"api_version":"1","generated_at":"2026-07-23T13:29:06+00:00","cve":"CVE-2022-39255","urls":{"html":"https://cve.report/CVE-2022-39255","api":"https://cve.report/api/cve/CVE-2022-39255.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2022-39255","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2022-39255"},"summary":{"title":"CVE-2022-39255","description":"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 that legitimately appear to have come from another person, without any indication such as a grey shield. Additionally, a sophisticated attacker cooperating with a malicious homeserver could employ this vulnerability to perform a targeted attack in order to send fake to-device messages appearing to originate from another user. This can allow, for example, to inject the key backup secret during a self-verification, to make a targeted device start using a malicious key backup spoofed by the homeserver. These attacks are possible due to a protocol confusion vulnerability that accepts to-device messages encrypted with Megolm instead of Olm. matrix-ios-sdk version 0.23.19 has been modified to only accept Olm-encrypted to-device messages. Out of caution, several other checks have been audited or added. This attack requires coordination between a malicious home server and an attacker, so those who trust their home servers do not need a workaround. 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This attack requires coordination between a malicious home server and an attacker, so those who trust their home servers do not need a workaround. 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