CVE-2026-5755 PUBLISHED

Denial of service via crafted TIFF file upload

Assigner: Mattermost
Reserved: 07.04.2026 Published: 22.05.2026 Updated: 22.05.2026

Mattermost versions 11.6.x <= 11.6.0, 11.5.x <= 11.5.2, 11.5.x <= 11.5.3, 11.4.x <= 11.4.4, 10.11.x <= 10.11.14 fail to validate the TIFF IFD offset in the image header before allocating memory, which allows authenticated users with file upload or posting permissions to cause a denial of service (server OOM) via uploading a crafted TIFF file or posting a URL that serves one.. Mattermost Advisory ID: MMSA-2026-00648

Metrics

CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
CVSS Score: 6.5

Product Status

Vendor Mattermost
Product Mattermost
Versions Default: unaffected
  • affected from 11.6.0 to 11.6.0 (incl.)
  • affected from 11.5.0 to 11.5.2 (incl.)
  • affected from 11.5.0 to 11.5.3 (incl.)
  • affected from 11.4.0 to 11.4.4 (incl.)
  • affected from 10.11.0 to 10.11.14 (incl.)
  • Version 11.7.0 is unaffected
  • Version 11.6.1 is unaffected
  • Version 11.5.3 is unaffected
  • Version 11.5.4 is unaffected
  • Version 11.4.5 is unaffected
  • Version 10.11.15 is unaffected

Solutions

Update Mattermost to versions 11.7.0, 11.6.1, 11.5.3, 11.5.4, 11.4.5, 10.11.15 or higher.

Credits

  • ZephrFish finder

References

Problem Types

  • CWE-400 Uncontrolled Resource Consumption CWE