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CVE PROGRAM SOURCE RECORD4.3 Medium

CVE-2026-16047

Board channel linking without read channel permission validation

Description

Mattermost versions 11.7.x <= 11.7.6, 10.11.x <= 10.11.21, 11.8.x <= 11.8.3 fail to validate that users have read access to a channel before linking a board to it, which allows an authenticated attacker to discover the membership of private channels on the same team via creating, patching, importing, or bulk-creating boards with an arbitrary channelId. Mattermost Advisory ID: MMSA-2026-00674

Affected products

Version statuses are supplied by the assigning organization. Consult the original record for detailed ranges and platform conditions.

Mattermost Mattermost

Default version status: unaffected

  • 11.7.0 to ≤ 11.7.6affected
  • 10.11.0 to ≤ 10.11.21affected
  • 11.8.0 to ≤ 11.8.3affected
  • 11.9.0unaffected
  • 11.7.7unaffected
  • 10.11.22unaffected
  • 11.8.4unaffected

References