CVE-2026-24458

Description

Mattermost versions 11.3.x <= 11.3.0, 11.2.x <= 11.2.2, 10.11.x <= 10.11.10 fail to properly handle very long passwords, which allows an attacker to overload the server CPU and memory via executing login attempts with multi-megabyte passwords. Mattermost Advisory ID: MMSA-2026-00587

CVSS Metrics

• v3.1•HIGH•Score: 7.5CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

EPSS Trends

Current EPSS score: 0.06%• Percentile: 20%

Techniques & Countermeasures

• CWE-770•Allocation of Resources Without Limits or Throttling

  The product allocates a reusable resource or group of resources on behalf of an actor without imposing any intended restrictions on the size or number of resources that can be allocated.

Affected Systems

• github.com/mattermost•mattermost-server

  ≥ 11.3.0-rc1+incompatible, < 11.3.1+incompatible | < 5.3.2-0.20260129164748-7201f42d955f | ≥ 10.11.0-rc1, < 10.11.11 | ≥ 11.2.0-rc1, < 11.2.3 | ≥ 11.3.0-rc1, < 11.3.1

• github.com/mattermost/mattermost-server•v5

  all

• github.com/mattermost/mattermost-server•v6

  all

• github.com/mattermost/mattermost/server•v8

  < 8.0.0-20260129164748-7201f42d955f

• mattermost•mattermost

  11.3.0 | ≥ 11.2.0, ≤ 11.2.2 | ≥ 10.11.0, ≤ 10.11.10

• mattermost•mattermost_server

  ≥ 10.11.0, < 10.11.11 | ≥ 11.2.0, < 11.2.3 | ≥ 11.3.0, < 11.3.1

References (5)

• https://mattermost.com/security-updates
• https://nvd.nist.gov/vuln/detail/CVE-2026-24458
• https://github.com/mattermost/mattermost/commit/7201f42d955f1bc44719b862132546626b60a180
• https://github.com/mattermost/mattermost
• https://github.com/advisories/GHSA-m5rv-56xx-hfc6