CVE-2026-15814CWE-409

CVE-2026-15814

Medium · published September 14, 2026

CVSS v3.1
6.5
EPSS
0%
Percentile
14.2
In the wild
Unconfirmed
What it is

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

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
0.00240 · 14.2th percentile
Weakness
CWE-409 · Improper Handling of Highly Compressed Data (Data Amplification)
Published
2026-09-14T15:17Z
Affected products (4)
ProductVersionsFixed in
mattermost/mattermost_server≥ 10.11.0, < 10.11.2310.11.23
mattermost/mattermost_server≥ 11.7.0, < 11.7.811.7.8
mattermost/mattermost_server≥ 11.8.0, < 11.8.511.8.5
mattermost/mattermost_server≥ 11.9.0, < 11.9.111.9.1
References (1)
https://mattermost.com/security-updates · [email protected]
EPSS history
Timeline
  • 16 SEP 04:25Z
    EPSS moved — → 0%
    epss
  • 14 SEP 10:39Z
    Uploading a crafted image causes excessive memory allocation in the Mattermost Server
    cvelistv5