CVE-2021-34813

low

Published — · Modified —

CVSS v3

—

CVSS v2

—

VIR risk

2.5

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.

Predictions

Exploit likelihood

20%

Patch ETA

—

Heuristic predictions, AS-IS, for prioritization only.

Mitigations

vendor Authored 2026-05-27

Vendor advisory: debian — https://security-tracker.debian.org/tracker/CVE-2021-34813

OS impact

OS	Version	Status	Fixed in
arch		fixed	`3.2.3-1`
debian	bookworm	fixed	`3.2.3~dfsg-3`
debian	bullseye	affected
debian	forky	fixed	`3.2.3~dfsg-3`
debian	sid	fixed	`3.2.3~dfsg-3`
debian	trixie	fixed	`3.2.3~dfsg-3`

References

https://security-tracker.debian.org/tracker/CVE-2021-34813

Verify integrity in audit chain (admin only). AS-IS.