CVE-2021-34813
9.8
CRITICAL · CVSS 3.1 · EPSS 4.3% (pctl 91)
In your normal cycle
Critical by CVSS (9.8), but no sign of active exploitation.
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.
Scoring
| CVSS | 9.8 (CRITICAL, v3.1) |
|---|---|
| Vector | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H |
| EPSS | 4.26% — more likely to be exploited than 91% of all CVEs |
| Weakness | CWE-787 |
| On CISA KEV | no |
| Public exploit | none known |
| Published | 2021-06-16 |
| Last modified | 2026-06-17 |
Affected (1)
| Vendor | Product |
|---|---|
| matrix | olm |
References
- https://gitlab.matrix.org/matrix-org/olm/-/commit/ccc0d122ee1b4d5e5ca4ec1432086be17d5f901b
- https://gitlab.matrix.org/matrix-org/olm/-/releases/3.2.3
- https://matrix.org/blog/2021/06/14/adventures-in-fuzzing-libolm
- https://gitlab.matrix.org/matrix-org/olm/-/commit/ccc0d122ee1b4d5e5ca4ec1432086be17d5f901b
- https://gitlab.matrix.org/matrix-org/olm/-/releases/3.2.3
- https://matrix.org/blog/2021/06/14/adventures-in-fuzzing-libolm
→ the Explorer · watch your stack · NVD