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CVE PROGRAM SOURCE RECORD5.4 Medium

CVE-2026-28735

GitHub OAuth Scope Validation

Description

Mattermost versions 11.6.x <= 11.6.0, 11.5.x <= 11.5.3, 11.4.x <= 11.4.4, 10.11.x <= 10.11.14 fail to validate the OAuth token scope on the callback which allows an authenticated Mattermost user to gain access to private repositories via modifying the scope parameter in the GitHub authorization URL.. Mattermost Advisory ID: MMSA-2026-00628

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

  • 11.6.0 to ≤ 11.6.0affected
  • 11.5.0 to ≤ 11.5.3affected
  • 11.4.0 to ≤ 11.4.4affected
  • 10.11.0 to ≤ 10.11.14affected
  • 11.7.0unaffected
  • 11.6.1unaffected
  • 11.5.4unaffected
  • 11.4.5unaffected
  • 10.11.15unaffected

References