CVE-2026-95666

Summary

Mattermost versions 11.9.x <= 11.9.1, 11.8.x <= 11.8.5, 11.7.x <= 11.7.10, 11.10.x <= 11.10.1 fail to limit the length of the post ID array accepted by the bulk reactions endpoint which allows an authenticated user to cause excessive database load via a crafted request to {{POST /api/v4/posts/ids/reactions}}.. Mattermost Advisory ID: MMSA-2026-00771

Affected Software

VendorProductVersion RangeStatus
MattermostMattermost11.9.0 <= 11.9.1affected
MattermostMattermost11.8.0 <= 11.8.5affected
MattermostMattermost11.7.0 <= 11.7.10affected
MattermostMattermost11.10.0 <= 11.10.1affected
MattermostMattermost11.11.0unaffected
MattermostMattermost11.9.2unaffected
MattermostMattermost11.8.6unaffected
MattermostMattermost11.7.11unaffected
MattermostMattermost11.10.2unaffected

Weaknesses

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

ADP Enrichment

CISA ADP Vulnrichment

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

References