EUVD-2026-60211
GHSA-496c-r634-6cgj
Severity by source
AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:L
Board Admin escalation implies read access to all board content, warranting C:L; availability is unaffected by the privilege grant itself.
Primary rating from Vendor (mattermost).
CVSS VectorVendor: mattermost
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:L
Lifecycle Timeline
1DescriptionCVE.org
Mattermost versions 11.7.x <= 11.7.6, 10.11.x <= 10.11.21 fail to prevent guest users from receiving Board Admin privileges during board archive import which allows a board member to escalate a guest user to Board Admin via importing a crafted .boardarchive file. Mattermost Advisory ID: MMSA-2026-00672
AnalysisAI
Privilege escalation in Mattermost's Boards feature allows a low-privileged board member to elevate a guest user to Board Admin by importing a specially crafted .boardarchive file. Affected are Mattermost versions 10.11.0 through 10.11.21 and 11.7.0 through 11.7.6. …
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Attack ChainAIDerived
Hypothetical attack flow derived from CVE metadata
Vulnerability AssessmentAI
| Exploitation | The attacker must hold at minimum a board member role on the target Mattermost instance - unauthenticated exploitation is not possible per the PR:L CVSS metric. … Additional conditions and limiting factors are described in the full assessment. |
| Risk Assessment | The CVSS 5.4 Medium score is broadly consistent with actual risk: network-reachable, low complexity, but gated behind existing board membership (PR:L). … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in. |
| Exploit Scenario | Full exploit scenario with step-by-step reproduction available after sign-in. |
| Remediation | Upgrade Mattermost to a version beyond the affected ranges for each branch: beyond 11.7.6 for the 11.7.x branch and beyond 10.11.21 for the 10.11.x branch, per the vendor's security updates page at https://mattermost.com/security-updates. … Detailed patch versions, workarounds, and compensating controls in full report. |
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External POC / Exploit Code
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