Is CVE-2026-14259 being exploited?

No public exploit is currently tracked.

How severe is CVE-2026-14259?

CVE-2026-14259 has a CVSS v3 severity of MEDIUM (4.3).

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CVE-2026-14259

Description

Mattermost versions 11.9.x <= 11.9.0, 11.8.x <= 11.8.4, 11.7.x <= 11.7.7, 10.11.x <= 10.11.22 fail to enforce board creation permissions when importing archive files which allows an authenticated non-guest team member to create Open or Private boards despite administrator restrictions via importing a crafted .boardarchive file. Mattermost Advisory ID: MMSA-2026-00712