CVE-2026-26233

Summary

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 Software

VendorProductVersion RangeStatus
MattermostMattermost11.4.0 <= 11.4.0affected
MattermostMattermost11.3.0 <= 11.3.1affected
MattermostMattermost11.2.0 <= 11.2.3affected
MattermostMattermost10.11.0 <= 10.11.11affected
MattermostMattermost11.5.0unaffected
MattermostMattermost11.4.1unaffected
MattermostMattermost11.3.2unaffected
MattermostMattermost11.2.4unaffected
MattermostMattermost10.11.12unaffected

Weaknesses

  • CWE-400: CWE-400 Uncontrolled Resource Consumption

ADP Enrichment

CISA ADP Vulnrichment

  • SSVC:
  • Exploitation: none
    • Automatable: no
    • Technical Impact: partial

References