CVE-2026-15754 | BDVDB-2026-360427 Detail

MattermostMattermost

Description#

Mattermost versions 11.7.x <= 11.7.6, 11.8.x <= 11.8.3 The access control policy unassign endpoint fails to re-validate that each target channel still belongs to the requesting admin's team, which allows an authenticated team administrator to remove ABAC (attribute-based access control) policy assignments from channels outside their team via the policy unassign API after a channel has been moved to another team.. Mattermost Advisory ID: MMSA-2026-00718

Impact#

Per CVSS v3.1: confidentiality impact none, integrity impact high, availability impact none. Attack vector: network.

Weaknesses#

CWE-863 Incorrect Authorization

References#

https://mattermost.com/security-updates

Exploit#

No public exploit known

History#

Version 12026-08-17Record published in the CVE List.

Published

Published: 2026-08-17
Last modified: 2026-08-17

Vendor information

Vendor: Mattermost
Product: Mattermost

All Mattermost vulnerabilities

Score

4.2 Medium

EPSS

less than 1%, Very Low

Estimated chance of exploitation in the next 30 days. EPSS percentile: 15.9.

KEV

Not listed in the CISA Known Exploited Vulnerabilities catalog.

Impact

Incorrect Authorization

Action

No specific action is recorded in the source data. Check the references for vendor guidance.

Affected Systems

Vulnerable
>= 11.7.0 and <= 11.7.6
Fixed
Not stated
Vulnerable
>= 11.8.0 and <= 11.8.3
Fixed
Not stated
Vulnerable
Not stated
Fixed
11.9.0
Vulnerable
Not stated
Fixed
11.7.7
Vulnerable
Not stated
Fixed
11.8.4

Scoring System

CVSS v4.0

Not available

CVSS v3.1

4.2 Medium

CVSS:3.1/AV:N/AC:H/PR:H/UI:R/S:U/C:N/I:H/A:N

Metric breakdown
Attack Vector	Network
Attack Complexity	High
Privileges Required	High
User Interaction	Required
Scope	Unchanged
Confidentiality	None
Integrity	High
Availability	None

CVSS v3.0

Not available

CVSS v2

Not available

Source: CVE List v5 (record); CISA KEV (kev, action); FIRST EPSS (epss).