CVE-2026-16047CWE-862broken-access-control

CVE-2026-16047

Medium · published August 17, 2026

CVSS v3.1
4.3
EPSS
0%
Percentile
18.2
In the wild
Unconfirmed
What it is

Mattermost versions 11.7.x <= 11.7.6, 10.11.x <= 10.11.21, 11.8.x <= 11.8.3 fail to validate that users have read access to a channel before linking a board to it, which allows an authenticated attacker to discover the membership of private channels on the same team via creating, patching, importing, or bulk-creating boards with an arbitrary channelId. Mattermost Advisory ID: MMSA-2026-00674

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:L/I:N/A:N
CVSS v4.0
Not supplied
EPSS
0.00270 · 18.2th percentile
Weakness
CWE-862 · Missing Authorization
Published
2026-08-17T19:16Z
Affected products (3)
ProductVersionsFixed in
mattermost/mattermost_server≥ 10.11.0, < 10.11.2210.11.22
mattermost/mattermost_server≥ 11.7.0, < 11.7.711.7.7
mattermost/mattermost_server≥ 11.8.0, < 11.8.411.8.4
References (1)
https://mattermost.com/security-updates · [email protected]
EPSS history
Timeline
  • 17 AUG 14:25Z
    Board channel linking without read channel permission validation
    cvelistv5