{"id":"CVE-2022-39248","state":"PUBLISHED","title":"matrix-android-sdk2 vulnerable to Olm/Megolm protocol confusion","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 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. matrix-android-sdk2 would then additionally sign such a key backup with its device key, spilling trust over to other devices trusting the matrix-android-sdk2 device. These attacks are possible due to a protocol confusion vulnerability that accepts to-device messages encrypted with Megolm instead of Olm. matrix-android-sdk2 version 1.5.1 has been modified to only accept Olm-encrypted to-device messages and to stop signing backups on a successful decryption. 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.","publishedAt":"2022-09-28T20:05:12.000Z","updatedAt":"2025-04-23T16:54:40.093Z","severity":{"score":8.6,"label":"High","version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:H/A:N","source":"GitHub_M"},"assigner":"GitHub_M","products":["matrix-org matrix-android-sdk2"],"affected":[{"vendor":"matrix-org","product":"matrix-android-sdk2","versions":[{"version":"< 1.5.1","status":"affected"}]}],"references":["https://matrix.org/blog/2022/09/28/upgrade-now-to-address-encryption-vulns-in-matrix-sdks-and-clients","https://github.com/matrix-org/matrix-android-sdk2/commit/77df720a238d17308deab83ecaa37f7a4740a17e","https://github.com/matrix-org/matrix-android-sdk2/releases/tag/v1.5.1","https://github.com/matrix-org/matrix-android-sdk2/security/advisories/GHSA-fpgf-pjjv-2qgm"],"weaknesses":["CWE-322","CWE-287"],"ingestedAt":"2026-10-29T19:50:29.496Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2022/39xxx/CVE-2022-39248.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.1","cveMetadata":{"cveId":"CVE-2022-39248","state":"PUBLISHED","datePublished":"2022-09-28T20:05:12.000Z","dateUpdated":"2025-04-23T16:54:40.093Z","assignerShortName":"GitHub_M","assignerOrgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateReserved":"2022-09-02T00:00:00.000Z"},"containers":{"cna":{"title":"matrix-android-sdk2 vulnerable to Olm/Megolm protocol confusion","descriptions":[{"lang":"en","value":"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 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. matrix-android-sdk2 would then additionally sign such a key backup with its device key, spilling trust over to other devices trusting the matrix-android-sdk2 device. These attacks are possible due to a protocol confusion vulnerability that accepts to-device messages encrypted with Megolm instead of Olm. matrix-android-sdk2 version 1.5.1 has been modified to only accept Olm-encrypted to-device messages and to stop signing backups on a successful decryption. 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."}],"affected":[{"vendor":"matrix-org","product":"matrix-android-sdk2","versions":[{"version":"< 1.5.1","status":"affected"}]}],"references":[{"url":"https://matrix.org/blog/2022/09/28/upgrade-now-to-address-encryption-vulns-in-matrix-sdks-and-clients","tags":["x_refsource_MISC"]},{"url":"https://github.com/matrix-org/matrix-android-sdk2/commit/77df720a238d17308deab83ecaa37f7a4740a17e","tags":["x_refsource_MISC"]},{"url":"https://github.com/matrix-org/matrix-android-sdk2/releases/tag/v1.5.1","tags":["x_refsource_MISC"]},{"url":"https://github.com/matrix-org/matrix-android-sdk2/security/advisories/GHSA-fpgf-pjjv-2qgm","tags":["x_refsource_CONFIRM"]}],"metrics":[{"cvssV3_1":{"attackComplexity":"LOW","attackVector":"NETWORK","availabilityImpact":"NONE","baseScore":8.6,"baseSeverity":"HIGH","confidentialityImpact":"NONE","integrityImpact":"HIGH","privilegesRequired":"NONE","scope":"CHANGED","userInteraction":"NONE","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:H/A:N","version":"3.1"}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-322","description":"CWE-322: Key Exchange without Entity Authentication","lang":"en","type":"CWE"}]},{"descriptions":[{"cweId":"CWE-287","description":"CWE-287: Improper Authentication","lang":"en","type":"CWE"}]}],"providerMetadata":{"shortName":"GitHub_M","dateUpdated":"2022-09-28T20:05:12.000Z","orgId":"a0819718-46f1-4df5-94e2-005712e83aaa"},"source":{"advisory":"GHSA-fpgf-pjjv-2qgm","discovery":"UNKNOWN"},"x_legacyV4Record":{"CVE_data_meta":{"ASSIGNER":"security-advisories@github.com","ID":"CVE-2022-39248","STATE":"PUBLIC","TITLE":"matrix-android-sdk2 vulnerable to Olm/Megolm protocol confusion"},"affects":{"vendor":{"vendor_data":[{"product":{"product_data":[{"product_name":"matrix-android-sdk2","version":{"version_data":[{"version_value":"< 1.5.1"}]}}]},"vendor_name":"matrix-org"}]}},"data_format":"MITRE","data_type":"CVE","data_version":"4.0","description":{"description_data":[{"lang":"eng","value":"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 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. matrix-android-sdk2 would then additionally sign such a key backup with its device key, spilling trust over to other devices trusting the matrix-android-sdk2 device. These attacks are possible due to a protocol confusion vulnerability that accepts to-device messages encrypted with Megolm instead of Olm. matrix-android-sdk2 version 1.5.1 has been modified to only accept Olm-encrypted to-device messages and to stop signing backups on a successful decryption. 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."}]},"impact":{"cvss":{"attackComplexity":"LOW","attackVector":"NETWORK","availabilityImpact":"NONE","baseScore":8.6,"baseSeverity":"HIGH","confidentialityImpact":"NONE","integrityImpact":"HIGH","privilegesRequired":"NONE","scope":"CHANGED","userInteraction":"NONE","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:H/A:N","version":"3.1"}},"problemtype":{"problemtype_data":[{"description":[{"lang":"eng","value":"CWE-322: Key Exchange without Entity Authentication"}]},{"description":[{"lang":"eng","value":"CWE-287: Improper Authentication"}]}]},"references":{"reference_data":[{"name":"https://matrix.org/blog/2022/09/28/upgrade-now-to-address-encryption-vulns-in-matrix-sdks-and-clients","refsource":"MISC","url":"https://matrix.org/blog/2022/09/28/upgrade-now-to-address-encryption-vulns-in-matrix-sdks-and-clients"},{"name":"https://github.com/matrix-org/matrix-android-sdk2/commit/77df720a238d17308deab83ecaa37f7a4740a17e","refsource":"MISC","url":"https://github.com/matrix-org/matrix-android-sdk2/commit/77df720a238d17308deab83ecaa37f7a4740a17e"},{"name":"https://github.com/matrix-org/matrix-android-sdk2/releases/tag/v1.5.1","refsource":"MISC","url":"https://github.com/matrix-org/matrix-android-sdk2/releases/tag/v1.5.1"},{"name":"https://github.com/matrix-org/matrix-android-sdk2/security/advisories/GHSA-fpgf-pjjv-2qgm","refsource":"CONFIRM","url":"https://github.com/matrix-org/matrix-android-sdk2/security/advisories/GHSA-fpgf-pjjv-2qgm"}]},"source":{"advisory":"GHSA-fpgf-pjjv-2qgm","discovery":"UNKNOWN"}}},"adp":[{"title":"CVE Program Container","references":[{"url":"https://matrix.org/blog/2022/09/28/upgrade-now-to-address-encryption-vulns-in-matrix-sdks-and-clients","tags":["x_refsource_MISC","x_transferred"]},{"url":"https://github.com/matrix-org/matrix-android-sdk2/commit/77df720a238d17308deab83ecaa37f7a4740a17e","tags":["x_refsource_MISC","x_transferred"]},{"url":"https://github.com/matrix-org/matrix-android-sdk2/releases/tag/v1.5.1","tags":["x_refsource_MISC","x_transferred"]},{"url":"https://github.com/matrix-org/matrix-android-sdk2/security/advisories/GHSA-fpgf-pjjv-2qgm","tags":["x_refsource_CONFIRM","x_transferred"]}],"providerMetadata":{"shortName":"CVE","orgId":"af854a3a-2127-422b-91ae-364da2661108","dateUpdated":"2024-08-03T12:00:43.445Z"}},{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2025-04-23T15:50:46.695381Z","id":"CVE-2022-39248","options":[{"Exploitation":"none"},{"Automatable":"yes"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2025-04-23T16:54:40.093Z"}}]}}}