CVE-2026-9693CWE-459

CVE-2026-9693

Low · published August 18, 2026

CVSS v3.1
3.5
EPSS
0%
Percentile
18.3
In the wild
Unconfirmed
What it is

Mattermost versions 10.11.x <= 10.11.20, 11.7.x <= 11.7.5 Mattermost fails to remove thread membership records when a user is removed from or leaves a team, which allows a previously removed user who is later re-invited to the team to view private channel thread root post content and metadata via the team threads API.. Mattermost Advisory ID: MMSA-2026-00682

The record
Technical detail
CVSS v3.1
3.5 · LOW
Vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:L/I:N/A:N
CVSS v4.0
Not supplied
EPSS
0.00271 · 18.3th percentile
Weakness
CWE-459 · Incomplete Cleanup
Published
2026-08-18T03:16Z
Affected products (2)
ProductVersionsFixed in
mattermost/mattermost_server≥ 10.11.0, < 10.11.2110.11.21
mattermost/mattermost_server≥ 11.7.0, < 11.7.611.7.6
References (1)
https://mattermost.com/security-updates · [email protected]
EPSS history
Timeline
  • 17 AUG 22:07Z
    Mattermost thread memberships persist after team removal, exposing private channel thread metadata on re-invite
    cvelistv5