CVE-2026-26233
Denial of Service via HTTP/2 single packet attack on login endpoint
CVSS Score
4.3
EPSS Score
0.1%
EPSS Percentile
24th
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
| CWE | CWE-400 |
| Vendor | mattermost |
| Product | mattermost |
| Published | Mar 25, 2026 |
| Last Updated | Mar 27, 2026 |
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CVSS v3 Breakdown
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L Attack Vector
Network
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
Low
Affected Versions
Mattermost / Mattermost
11.4.0 ≤ 11.4.0 11.3.0 ≤ 11.3.1 11.2.0 ≤ 11.2.3 10.11.0 ≤ 10.11.11
Credits
Axel Larsson & Jakob Ristner