Mattermost <11.5 mmctl Terminal Escape Sequences Vulnerability (CVE-2026-3108)
CVE-2026-3108 Published on March 26, 2026

Terminal Escape Injection in mmctl Report Posts Command
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

Vendor Advisory NVD

Vulnerability Analysis

CVE-2026-3108 is exploitable with network access, requires user interaction and a small amount of user privileges. This vulnerability is consided to have a high level of attack complexity. The potential impact of an exploit of this vulnerability is considered to be very high.

Attack Vector:
NETWORK
Attack Complexity:
HIGH
Privileges Required:
LOW
User Interaction:
REQUIRED
Scope:
CHANGED
Confidentiality Impact:
HIGH
Integrity Impact:
HIGH
Availability Impact:
HIGH

Weakness Type

Improper Neutralization of Escape, Meta, or Control Sequences

The software receives input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could be interpreted as escape, meta, or control character sequences when they are sent to a downstream component. As data is parsed, an injected/absent/malformed delimiter may cause the process to take unexpected actions.


Products Associated with CVE-2026-3108

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MatterMost
 

Affected Versions

Mattermost:

Exploit Probability

EPSS
0.04%
Percentile
12.81%

EPSS (Exploit Prediction Scoring System) scores estimate the probability that a vulnerability will be exploited in the wild within the next 30 days. The percentile shows you how this score compares to all other vulnerabilities.