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CVE PROGRAM SOURCE RECORD6.5 Medium

CVE-2026-10819

Mattermost Server Denial of Service via Animated GIF Emoji Upload

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Status
Published
Published
Updated
Assigning organization
Mattermost

Description

Mattermost versions 11.6.x <= 11.6.5, 10.11.x <= 10.11.20, 11.8.x <= 11.8.1, 11.7.x <= 11.7.4 fail to limit the number of frames and enforce the file size cap on animated GIF uploads, which allows an authenticated attacker to cause a denial of service via a crafted animated GIF uploaded as a custom emoji.. Mattermost Advisory ID: MMSA-2026-00695

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 ≤ 11.6.5affected
  • 10.11.0 to ≤ 10.11.20affected
  • 11.8.0 to ≤ 11.8.1affected
  • 11.7.0 to ≤ 11.7.4affected
  • 11.9.0unaffected
  • 11.6.6unaffected
  • 10.11.21unaffected
  • 11.8.2unaffected
  • 11.7.5unaffected

References