CVE-2021-34813

moderate-risk
Published 2021-06-16

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.

Do I need to act?

~
4.5% chance of exploitation in next 30 days
EPSS score — moderate exploit probability
-
Not on CISA KEV list
No confirmed active exploitation reported to CISA
+
Fix available
Upgrade to: d856c441b69fa2d3bb081c35a077725ece3ec0e5, ccc0d122ee1b4d5e5ca4ec1432086be17d5f901b
9
CVSS 9.8/10 Critical
NETWORK / LOW complexity

Affected Products (1)

Olm

Affected Vendors

Matrix

References (6)

Patch https://gitlab.matrix.org/matrix-org/olm/-/commit/ccc0d122ee1b4d5e5ca4ec1432086b...
Release Notes https://gitlab.matrix.org/matrix-org/olm/-/releases/3.2.3
Exploit https://matrix.org/blog/2021/06/14/adventures-in-fuzzing-libolm
Patch https://gitlab.matrix.org/matrix-org/olm/-/commit/ccc0d122ee1b4d5e5ca4ec1432086b...
Release Notes https://gitlab.matrix.org/matrix-org/olm/-/releases/3.2.3
Exploit https://matrix.org/blog/2021/06/14/adventures-in-fuzzing-libolm
45
/ 100
moderate-risk
Severity 32/34 · Critical
Exploitability 8/34 · Low
Exposure 5/34 · Minimal