Riskcovery

CVE-2026-6046

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

State
Published
Severity
5.3 Medium
Published
Jun 12, 2026
Updated
Jun 12, 2026
Reserved
Apr 9, 2026

Read the record on cve.org

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

Scores

CVSSScoreVectorSource
3.15.3 MediumCVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:N/A:NMattermost

Weaknesses

  • CWE-200 Exposure of Sensitive Information to an Unauthorized Actor

Affected Products

ProductVersions
MattermostMattermost
  • 11.6.0 through 11.6.1Affected
  • 11.5.0 through 11.5.4Affected
  • 10.11.0 through 10.11.15Affected
  • 10.11.0 through 10.11.16Affected
  • 11.7.0Not affected
  • 11.6.2Not affected
  • 11.5.5Not affected
  • 10.11.16Not affected
  • 10.11.17Not affected

References

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