CVE-2026-3108
Mattermost allows attackers to manipulate administrator terminals via crafted messages containing ANSI and OSC escape sequences
8.0
HIGH
CVSS 3.1
EPSS 0.02%
Description
Mattermost versions 11.2.x <= 11.2.2, 10.11.x <= 10.11.10, 11.4.x <= 11.4.0, 11.3.x <= 11.3.1 fail to sanitize user-controlled post content in the mmctl commands terminal output which allows attackers to manipulate administrator terminals via crafted messages containing ANSI and OSC escape sequences that enable screen manipulation, fake prompts, and clipboard hijacking. Mattermost Advisory ID: MMSA-2026-00599.
How to fix CVE-2026-3108
To remediate CVE-2026-3108, upgrade the affected package to a fixed version below.
- —upgrade to 11.4.1 or later
Is CVE-2026-3108 being exploited?
Low — EPSS is 0.0%, meaning exploitation activity has not been observed at scale.
Affected packages (1)
- >= 11.4.0-rc1, < 11.4.1
CVSS scores
| Source | Version | Severity | Vector |
|---|---|---|---|
| osv | CVSS 3.1 | HIGH8.0 | CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:C/C:H/I:H/A:H |