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CVE PROGRAM SOURCE RECORD5.3 Medium

CVE-2026-6046

Plugin bot username conflict allows user account to be used as bot identity in Mattermost Server

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Status
Published
Published
Updated
Assigning organization
Mattermost

Description

Mattermost versions 11.6.x <= 11.6.1, 11.5.x <= 11.5.4, 10.11.x <= 10.11.15, 10.11.x <= 10.11.16 fail to validate that a username returned during bot registration belongs to a bot account, which allows an unprivileged attacker to intercept private messages sent by plugins via direct message channels by pre-registering a user account with a predictable plugin bot username.. Mattermost Advisory ID: MMSA-2026-00649

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 ≤ 11.6.1affected
  • 11.5.0 to ≤ 11.5.4affected
  • 10.11.0 to ≤ 10.11.15affected
  • 10.11.0 to ≤ 10.11.16affected
  • 11.7.0unaffected
  • 11.6.2unaffected
  • 11.5.5unaffected
  • 10.11.16unaffected
  • 10.11.17unaffected

References