Bug 2448235 (CVE-2026-26230)

Summary: CVE-2026-26230 github.com/mattermost/mattermost-server: Team Admin Privilege Escalation to Demote Members to Guest
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
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Priority: low    
Version: unspecifiedKeywords: Security
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Hardware: All   
OS: Linux   
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A permissions validation flaw has been discovered in mattermost server. Affected versions fail to properly validate permission requirements in the team member roles API endpoint which allows team administrators to demote members to guest role.
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
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Bug Depends On: 2448250, 2448251    
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Description OSIDB Bzimport 2026-03-16 21:02:05 UTC
Mattermost versions 10.11.x <= 10.11.10 fail to properly validate permission requirements in the team member roles API endpoint which allows team administrators to demote members to guest role. Mattermost Advisory ID: MMSA-2025-00531