CVE-2021-34813

CriticalCVSS 9.8/10Last modified Jun 17, 2026

Description

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.

Metrics

CVSS 3.1 9.8/10CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Weakness enumeration

CWE-787

Affected software

Vendor	Product	Versions
n/a	n/a	n/a

References

https://gitlab.matrix.org/matrix-org/olm/-/commit/ccc0d122ee1b4d5e5ca4ec1432086be17d5f901bPatch, Vendor Advisory
https://gitlab.matrix.org/matrix-org/olm/-/releases/3.2.3Release Notes, Vendor Advisory
https://matrix.org/blog/2021/06/14/adventures-in-fuzzing-libolmExploit, Patch, Vendor Advisory
https://gitlab.matrix.org/matrix-org/olm/-/commit/ccc0d122ee1b4d5e5ca4ec1432086be17d5f901bPatch, Vendor Advisory
https://gitlab.matrix.org/matrix-org/olm/-/releases/3.2.3Release Notes, Vendor Advisory
https://matrix.org/blog/2021/06/14/adventures-in-fuzzing-libolmExploit, Patch, Vendor Advisory

Timeline

Published: Jun 16, 2021
Last modified: Jun 17, 2026
NVD status: Modified

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