CVE-2026-4915CWE-754

Server panic via outgoing webhook responses

Medium · published May 25, 2026

CVSS v3.1
6.5
EPSS
0%
Percentile
28.2
In the wild
Unconfirmed
What it is

Mattermost versions 11.6.x <= 11.6.0, 11.5.x <= 11.5.3, 11.4.x <= 11.4.4, 10.11.x <= 10.11.14 fail to filter nil elements from outgoing webhook attachment payloads before processing, which allows an authenticated user to cause a denial of service (server process termination) via a crafted webhook callback response containing a null attachment entry.. Mattermost Advisory ID: MMSA-2026-00641

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
0.00357 · 28.2th percentile
Weakness
CWE-754 · Improper Check for Unusual or Exceptional Conditions
Published
2026-05-25T07:10Z
EPSS history
Timeline
  • 25 MAY 07:10Z
    Server panic via outgoing webhook responses
    cvelistv5