CVE-2021-44538
Description
The olm_session_describe function in Matrix libolm before 3.2.7 is vulnerable to a buffer overflow. The Olm session object represents a cryptographic channel between two parties. Therefore, its state is partially controllable by the remote party of the channel. Attackers can construct a crafted sequence of messages to manipulate the state of the receiver's session in such a way that, for some buffer sizes, a buffer overflow happens on a call to olm_session_describe. Furthermore, safe buffer sizes were undocumented. The overflow content is partially controllable by the attacker and limited to ASCII spaces and digits. The known affected products are Element Web And SchildiChat Web.
Predictions
Heuristic predictions, AS-IS, for prioritization only.
Mitigations
No mitigations published for this CVE yet.
The vendor-content worker queues fetches as references arrive (check back in a few minutes). Or — if you've already worked around this in production — publish your fix to the community-verified tier.
✚ Propose a mitigation on Community → Mitigations published via the community go through AI scoring + 2 human reviewers + 7-day silent objection window before landing here withsource_tier=community-verified.
OS impact
SUSE Affected 1 release
| Version | Status | Fixed in |
|---|---|---|
| — | Affected | — |
Arch Fixed 1 release
| Version | Status | Fixed in |
|---|---|---|
| — | Fixed | 1.9.7-1 |
Debian Fixed 5 releases
| Version | Status | Fixed in |
|---|---|---|
| trixie | Fixed | 3.2.8~dfsg-1 |
| sid | Fixed | 3.2.8~dfsg-1 |
| forky | Fixed | 3.2.8~dfsg-1 |
| bullseye | Fixed | 1:91.4.1-1~deb11u1 |
| bookworm | Fixed | 3.2.8~dfsg-1 |
References
Community-verified mitigations for this CVE will appear above when contributors publish them.
Verify integrity in audit chain (admin only). AS-IS.