{"id":"UBUNTU-CVE-2021-34813","details":"Matrix libolm before 3.2.3 allows a malicious Matrix homeserver to crash a client (while it is attempting to retrieve an Olm encrypted room key backup from the homeserver) because olm_pk_decrypt has a stack-based buffer overflow. Remote code execution might be possible for some nonstandard build configurations.","modified":"2026-04-22T12:55:41.669757Z","published":"2021-06-16T18:15:00Z","related":["USN-5194-1"],"upstream":["CVE-2021-34813"],"references":[{"type":"REPORT","url":"https://ubuntu.com/security/CVE-2021-34813"},{"type":"REPORT","url":"https://gitlab.matrix.org/matrix-org/olm/-/commit/ccc0d122ee1b4d5e5ca4ec1432086be17d5f901b"},{"type":"REPORT","url":"https://gitlab.matrix.org/matrix-org/olm/-/releases/3.2.3"},{"type":"REPORT","url":"https://matrix.org/blog/2021/06/14/adventures-in-fuzzing-libolm"},{"type":"ADVISORY","url":"https://ubuntu.com/security/notices/USN-5194-1"},{"type":"REPORT","url":"https://www.cve.org/CVERecord?id=CVE-2021-34813"}],"affected":[{"package":{"name":"olm","ecosystem":"Ubuntu:Pro:20.04:LTS","purl":"pkg:deb/ubuntu/olm@3.1.3+dfsg-2ubuntu0.1~esm1?arch=source&distro=esm-apps/focal"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"3.1.3+dfsg-2ubuntu0.1~esm1"}]}],"versions":["3.1.3+dfsg-2","3.1.3+dfsg-2build1","3.1.3+dfsg-2build2"],"ecosystem_specific":{"availability":"Available with Ubuntu Pro: https://ubuntu.com/pro","binaries":[{"binary_name":"libolm3","binary_version":"3.1.3+dfsg-2ubuntu0.1~esm1"},{"binary_name":"python3-olm","binary_version":"3.1.3+dfsg-2ubuntu0.1~esm1"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2021/UBUNTU-CVE-2021-34813.json"}}],"schema_version":"1.7.5","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H"},{"type":"Ubuntu","score":"medium"}]}