CVE-2026-5755

MEDIUM

Mattermost - Denial of Service via Crafted TIFF File Upload

Title source: rule
STIX 2.1

Description

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

References (1)

Core 1
Core References
Vendor Advisory vendor-advisory
MMSA-2026-00648
https://mattermost.com/security-updates

Scores

CVSS v3 6.5
EPSS 0.0003
EPSS Percentile 9.7%
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

CISA SSVC

Vulnrichment
Exploitation none
Automatable no
Technical Impact partial

Details

CWE
CWE-400
Status published
Products (11)
Mattermost/Mattermost 10.11.0 - 10.11.14
Mattermost/Mattermost 10.11.15
Mattermost/Mattermost 11.4.0 - 11.4.4
Mattermost/Mattermost 11.4.5
Mattermost/Mattermost 11.5.0 - 11.5.2
Mattermost/Mattermost 11.5.0 - 11.5.3
Mattermost/Mattermost 11.5.3
Mattermost/Mattermost 11.5.4
Mattermost/Mattermost 11.6.0
Mattermost/Mattermost 11.6.1
... and 1 more
Published May 22, 2026
Tracked Since May 22, 2026