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CVE PROGRAM SOURCE RECORD4.3 Medium

CVE-2026-6339

Missing request origin validation on burn-on-read reveal endpoint

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Status
Published
Published
Updated
Assigning organization
Mattermost

Description

Mattermost versions 11.5.x <= 11.5.1, 11.4.x <= 11.4.3 fail to validate the X-Requested-With header on the burn-on-read reveal endpoint which allows an authenticated channel member to force the reveal of a burn-on-read message without recipient consent via a crafted Markdown image tag.. Mattermost Advisory ID: MMSA-2026-00636

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

  • 11.5.0 to ≤ 11.5.1affected
  • 11.4.0 to ≤ 11.4.3affected
  • 11.6.0unaffected
  • 11.5.2unaffected
  • 11.4.4unaffected

References