CVE-2026-3115 — Incorrect Authorization in Mattermost Mattermost Server V8

CWE-863 — Incorrect Authorization5 documents5 sources
Severity
4.3MEDIUMNVD
EPSS
0.0%
top 91.63%
CISA KEV
Not in KEV
Exploit
No known exploits
Affected products
3
Github.com Mattermost Mattermost Server V8Mattermost ServerMattermost
Timeline
PublishedMar 26

Description

Mattermost versions 11.2.x <= 11.2.2, 10.11.x <= 10.11.10, 11.4.x <= 11.4.0, 11.3.x <= 11.3.1 fail to apply view restrictions when retrieving group member IDs, which allows authenticated guest users to enumerate user IDs outside their allowed visibility scope via the group retrieval endpoint.. Mattermost Advisory ID: MMSA-2026-00594

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:NExploitability: 2.8 | Impact: 1.4

Affected Packages3 packages

▶NVDmattermost/mattermost_server10.11.0 — 10.11.11+3
▶CVEListV5mattermost/mattermost11.2.0 — 11.2.2+3

🔴Vulnerability Details

3
GHSA
Mattermost allows authenticated guest users to enumerate user IDs outside their allowed visibility scope↗2026-03-26
▶
CVEList
Guest users can view group member IDs without respecting view restrictions↗2026-03-26
▶
OSV
Mattermost allows authenticated guest users to enumerate user IDs outside their allowed visibility scope↗2026-03-26
▶

🕵️Threat Intelligence

1
Wiz
CVE-2026-3115 Impact, Exploitability, and Mitigation Steps | Wiz↗
▶
CVE-2026-3115 — Incorrect Authorization | cvebase