CVE-2026-6342CWE-863broken-access-control

CVE-2026-6342

Medium · published May 18, 2026

CVSS v3.1
4.3
EPSS
0%
Percentile
16.0
In the wild
Unconfirmed
What it is

Mattermost Plugins versions <=11.5 11.1.5 10.13.11 11.3.4.0 fail to appropriately check for valid namespaces which allows plugin users to create subscriptions to groups that were not whitelisted via creating groups that share the same prefix as a whitelisted group. Mattermost Advisory ID: MMSA-2026-00601

The record
Technical detail
CVSS v3.1
4.3 · MEDIUM
Vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N
CVSS v4.0
Not supplied
EPSS
0.00254 · 16.0th percentile
Weakness
CWE-863 · Incorrect Authorization
Published
2026-05-18T12:16Z
Affected products (3)
ProductVersionsFixed in
mattermost/mattermost_server≥ 10.13.0, ≤ 10.13.11—
mattermost/mattermost_server≥ 11.1.0, ≤ 11.1.5—
mattermost/mattermost_server≥ 11.3.0, ≤ 11.3.4—
References (1)
https://mattermost.com/security-updates · [email protected]
EPSS history
Timeline
  • 18 MAY 07:00Z
    Group prefix matching bypass for subscriptions
    cvelistv5