CVE-2026-5755

Denial of service via crafted TIFF file upload

State: Published
Severity: 6.5 Medium
Published: May 22, 2026
Updated: May 22, 2026
Reserved: Apr 7, 2026

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

Scores

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

Weaknesses

CWE-400 Uncontrolled Resource Consumption

Affected Products

Product	Versions
MattermostMattermost	11.6.0 through 11.6.0Affected 11.5.0 through 11.5.2Affected 11.5.0 through 11.5.3Affected 11.4.0 through 11.4.4Affected 10.11.0 through 10.11.14Affected 11.7.0Not affected 11.6.1Not affected 11.5.3Not affected 11.5.4Not affected 11.4.5Not affected 10.11.15Not affected

References

MMSA-2026-00648vendor-advisory

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