CVE-2026-18795CWE-862broken-access-control

CVE-2026-18795

Medium · published October 16, 2026

CVSS v3.1
6.4
EPSS
0%
Percentile
3.9
In the wild
Unconfirmed
What it is

Mattermost versions 11.10.x <= 11.10.0, 11.7.x <= 11.7.9, 11.9.x <= 11.9.1, 11.8.x <= 11.8.5 fail to enforce DM/GM check on server side which allows an authenticated user to quarantine a post belonging to DM or GM via direct API call.. Mattermost Advisory ID: MMSA-2026-00756

The record
Technical detail
CVSS v3.1
6.4 · MEDIUM
Vector
CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:L/A:L
CVSS v4.0
Not supplied
EPSS
0.00150 · 3.9th percentile
Weakness
CWE-862 · Missing Authorization
Published
2026-10-16T11:17Z
References (1)
https://mattermost.com/security-updates · [email protected]
EPSS history
Timeline
  • 17 OCT 03:28Z
    EPSS moved — → 0%
    epss
  • 16 OCT 07:01Z
    Missing server side validation allowed user to quarantine a DM and GM post
    cvelistv5
  • 16 OCT 07:01Z
    Missing server side validation allowed user to quarantine a DM and GM post
    cvelistv5