CVE-2026-5755

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 serve...

CVE-2026-5755

CVE-2026-5755 affects Mattermost releases 11.6.x up to 11.6.0, 11.5.x up to 11.5.2/11.5.3, 11.4.x up to 11.4.4, and 10.11.x up to 10.11.14. The issue arises from failure to validate the TIFF IFD offset in the image header before memory allocation, allowing authenticated users with file upload or ...