{
  "affected": [
    {
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "77df720a238d17308deab83ecaa37f7a4740a17e"
            }
          ],
          "repo": "https://github.com/matrix-org/matrix-android-sdk2",
          "type": "GIT"
        },
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "e1b2844afce399811162b1015c0d4740e6d9de9a"
            }
          ],
          "repo": "https://github.com/matrix-org/matrix-android-sdk2",
          "type": "GIT"
        },
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "77df720a238d17308deab83ecaa37f7a4740a17e"
            }
          ],
          "repo": "https://github.com/matrix-org/matrix-android-sdk2",
          "type": "GIT"
        },
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "e1b2844afce399811162b1015c0d4740e6d9de9a"
            }
          ],
          "repo": "https://github.com/matrix-org/matrix-android-sdk2",
          "type": "GIT"
        }
      ]
    }
  ],
  "aliases": [
    "GHSA-fpgf-pjjv-2qgm"
  ],
  "database_specific": {
    "cna_assigner": "GitHub_M",
    "cwe_ids": [
      "CWE-287",
      "CWE-322"
    ],
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2022/39xxx/CVE-2022-39248.json"
  },
  "details": "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.",
  "id": "CVE-2022-39248",
  "modified": "2026-04-01T23:09:07.509235215Z",
  "published": "2022-09-28T20:05:12Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/matrix-org/matrix-android-sdk2/releases/tag/v1.5.1"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2022/39xxx/CVE-2022-39248.json"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/matrix-org/matrix-android-sdk2/security/advisories/GHSA-fpgf-pjjv-2qgm"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2022-39248"
    },
    {
      "type": "FIX",
      "url": "https://github.com/matrix-org/matrix-android-sdk2/commit/77df720a238d17308deab83ecaa37f7a4740a17e"
    },
    {
      "type": "ARTICLE",
      "url": "https://matrix.org/blog/2022/09/28/upgrade-now-to-address-encryption-vulns-in-matrix-sdks-and-clients"
    }
  ],
  "schema_version": "1.7.3",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:H/A:N",
      "type": "CVSS_V3"
    }
  ],
  "summary": "matrix-android-sdk2 vulnerable to Olm/Megolm protocol confusion"
}