CVE-2026-5755CWE-400

Denial of service via crafted TIFF file upload

Medium · published May 22, 2026

CVSS v3.1
6.5
EPSS
0%
Percentile
35.2
In the wild
Unconfirmed
What it is

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

The record
Technical detail
CVSS v3.1
6.5 · MEDIUM
Vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
CVSS v4.0
Not supplied
EPSS
0.00420 · 35.2th percentile
Weakness
CWE-400 · Uncontrolled Resource Consumption
Published
2026-05-22T10:18Z
EPSS history
Timeline
  • 22 MAY 10:18Z
    Denial of service via crafted TIFF file upload
    cvelistv5