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.
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
Debian
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian 14 | olm | 3.2.3~dfsg-3 | — |
| Debian 13 | olm | 3.2.3~dfsg-3 | — |
| Debian 12 | olm | 3.2.3~dfsg-3 | — |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu Pro 20.04 LTS | olm | 3.1.3+dfsg-2ubuntu0.1~esm1 | USN-5194-1 |
Advisories 1
- USN-5194-1 olm vulnerability Ubuntu Security Notices (USN) · Apr 22, 2026