Terminal Escape Injection in mmctl Report Posts Command

Summary

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

Timeline

1. Mar 26, 2026, 12:00 AM UTCCISA SSVC assessment

   Exploitation: none · Automatable: no · Technical impact: total

2. Mar 26, 2026, 4:16 PM UTCCVE published
3. Mar 27, 2026, 3:55 AM UTCRecord last updated

Affected versions

• Mattermost Mattermost

  From 11.2.0 · through 11.2.2; From 10.11.0 · through 10.11.10; From 11.4.0 · through 11.4.0; From 11.3.0 · through 11.3.1

• github.com/mattermost/mattermost/server/v8Go

  From 11.4.0-rc1 · fixed in 11.4.1

• github.com/mattermost/mattermost/server/v8Go

  From 11.3.0-rc1 · fixed in 11.3.2

• github.com/mattermost/mattermost/server/v8Go

  From 11.2.0-rc1 · fixed in 11.2.3

• github.com/mattermost/mattermost/server/v8Go

  From 10.11.0-rc1 · fixed in 10.11.11

• github.com/mattermost/mattermost/server/v8Go

  From 8.0.0-20260105080200-d27a2195068d · fixed in 8.0.0-20260217110922-b7d4a1f1f59b

• github.com/mattermost/mattermost-serverGo

  From 10.11.0-rc1+incompatible · fixed in 10.11.11+incompatible; From 11.2.0-rc1+incompatible · fixed in 11.2.3+incompatible; From 11.3.0-rc1+incompatible · fixed in 11.3.2+incompatible; From 11.4.0-rc1+incompatible · fixed in 11.4.1+incompatible

• github.com/mattermost/mattermost-server/v5Go

  All versions

• github.com/mattermost/mattermost-server/v6Go

  All versions

References 1