CVE-2026-3108
Mattermost mmctl allows ANSI escape sequences to manipulate admin terminals.
Is CVE-2026-3108 being exploited?
Not confirmed. CVE-2026-3108 does not appear in CISA's Known Exploited Vulnerabilities catalog, which records only exploitation that has been observed and reported publicly. That is evidence of absence of a report, not evidence the flaw is unattacked. EPSS currently estimates a 0.28% probability of exploitation in the next 30 days.
How severe is CVE-2026-3108?
CVE-2026-3108 is rated High with a CVSS score of 8.0. Severity describes how bad exploitation would be, not how likely it is: pair it with exploitation evidence before deciding what to patch first.
Is there a patch for CVE-2026-3108?
Yes. A fix has been recorded for CVE-2026-3108. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2026-3108 affect?
CVE-2026-3108 affects Mattermost 11.2.x <= 11.2.2, Mattermost 10.11.x <= 10.11.10, Mattermost 11.4.x <= 11.4.0, Mattermost 11.3.x <= 11.3.1. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-3108?
Upgrade to fixed Mattermost release per MMSA-2026-00599
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
Crafted ANSI/OSC sequences in admin MMCTL output enable screen manipulation, fake prompts, and clipboard hijacking.
Immediate action required
- affected>= 11.2.0 and <= 11.2.2
- affected>= 10.11.0 and <= 10.11.10
- affected<= 11.4.0
- affected>= 11.3.0 and <= 11.3.1
As published in the CVE Program record. A version outside these ranges is not a statement that it is unaffected — vendors sometimes understate a range, and distribution-backported builds carry upstream numbers that do not reflect what was patched into them.