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MEDIUM · 4.2

CVE-2026-15754

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 all...

Vulnerability 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

CVSS Score

4.2

MEDIUM

CVSS:3.1/AV:N/AC:H/PR:H/UI:R/S:U/C:N/I:H/A:N
Attack Vector
NETWORK
Attack Complexity
HIGH
Privileges Required
HIGH
User Interaction
REQUIRED
Scope
UNCHANGED
Confidentiality
NONE
Integrity
HIGH
Availability
NONE

Affected Products

VendorProductVersions
MattermostMattermost Server>= 11.7.0, < 11.7.7

Related Weaknesses (CWE)

CWE-863

References

FAQ

What is CVE-2026-15754?

CVE-2026-15754 is a vulnerability with a CVSS score of 4.2 (MEDIUM). 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 all...

How severe is CVE-2026-15754?

CVE-2026-15754 has been rated MEDIUM with a CVSS base score of 4.2/10. Review the CVSS metrics above for detailed severity breakdown.

Is there a patch for CVE-2026-15754?

Check the references section above for vendor advisories and patch information. Affected products include: Mattermost Mattermost Server.