CVE-2026-15814

Uploading a crafted image causes excessive memory allocation in the Mattermost Server

State: Published
Severity: 6.5 Medium
Published: Sep 14, 2026
Updated: Sep 14, 2026
Reserved: Jul 15, 2026

Description

Mattermost versions 11.9.x <= 11.9.0, 11.8.x <= 11.8.4, 11.7.x <= 11.7.7, 10.11.x <= 10.11.22 fail to limit the amount of memory allocated when decoding uploaded image files which allows an authenticated user to cause excessive server memory consumption and potential denial of service via uploading a specially crafted image as a profile picture, channel file attachment, team icon, or custom brand image. Mattermost Advisory ID: MMSA-2026-00719

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-409 Improper Handling of Highly Compressed Data (Data Amplification)

Affected Products

Product	Versions
MattermostMattermost	11.9.0 through 11.9.0Affected 11.8.0 through 11.8.4Affected 11.7.0 through 11.7.7Affected 10.11.0 through 10.11.22Affected 11.10.0Not affected 11.9.1Not affected 11.8.5Not affected 11.7.8Not affected 10.11.23Not affected

References

MMSA-2026-00719vendor-advisory

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