CVE-2026-26233
MEDIUM4.3EPSS 0.12%Mattermost doesn't rate limit login requests, allowing DoS
Published: 3/25/2026Modified: 4/6/2026
Description
Mattermost versions 11.4.x <= 11.4.0, 11.3.x <= 11.3.1, 11.2.x <= 11.2.3, 10.11.x <= 10.11.11 fail to rate limit login requests which allows unauthenticated remote attackers to cause denial of service (server crash and restart) via HTTP/2 single packet attack with 100+ parallel login requests.. Mattermost Advisory ID: MMSA-2025-00566
Affected packages (2)
- Go/github.com/mattermost/mattermost-server>= 11.4.0-rc1, < 11.4.1
- Go/github.com/mattermost/mattermost-server>= 10.11.0-rc1+incompatible, < 10.11.12+incompatible, >= 11.2.0-rc1+incompatible, < 11.2.4+incompatible, >= 11.3.0-rc1+incompatible, < 11.3.2+incompatible, >= 11.4.0-rc1+incompatible, < 11.4.1+incompatible
CVSS scores
| Source | Version | Severity | Vector |
|---|---|---|---|
| osv | CVSS 3.1 | MEDIUM4.3 | CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L |