CVE-2026-5740
EUVD-2026-3142622.05.2026, 11:16
Mattermost versions 11.6.x <= 11.6.0, 11.5.x <= 11.5.3, 11.4.x <= 11.4.4, 10.11.x <= 10.11.14 fail to properly validate msgpack-encoded WebSocket frames before memory allocation which allows an unauthenticated remote attacker to crash the server process and cause a full service outage for all users via a crafted binary WebSocket message sent to the public WebSocket endpoint.. Mattermost Advisory ID: MMSA-2026-00647Enginsight
Affected Products (NVD)
| Vendor | Product | Version |
|---|---|---|
| mattermost | mattermost_server | 10.11.0 ≤ 𝑥 < 10.11.15 |
| mattermost | mattermost_server | 11.4.0 ≤ 𝑥 < 11.4.5 |
| mattermost | mattermost_server | 11.5.0 ≤ 𝑥 < 11.5.4 |
| mattermost | mattermost_server | 11.6.0 ≤ 𝑥 < 11.6.1 |
𝑥
= Vulnerable software versions
Early Detection
Affected products identified ahead of NVD analysis through intelligence sources.
| Vendor | Product | Version | Source |
|---|---|---|---|
| mattermost | mattermost | 𝑥 ≤ 11.6.0 | CNA |
| mattermost | mattermost | 11.5.0 ≤ 𝑥 ≤ 11.5.3 | CNA |
| mattermost | mattermost | 11.4.0 ≤ 𝑥 ≤ 11.4.4 | CNA |
| mattermost | mattermost | 10.11.0 ≤ 𝑥 ≤ 10.11.14 | CNA |
Common Weakness Enumeration
References