GHSA-vqp5-2mrp-qqxgLowCVSS 3.5

Mattermost doesn't validate the Host header when constructing response URLs for custom slash command

Published
May 18, 2026
Last Modified
June 1, 2026

🔗 CVE IDs covered (1)

CVE-2026-6333 →

📋 Description

Mattermost versions 11.5.x <= 11.5.1, 10.11.x <= 10.11.13 fail to validate the Host header when constructing response URLs for custom slash commands which allows an authenticated attacker to redirect slash command responses to an attacker-controlled server via a spoofed Host header.. Mattermost Advisory ID: MMSA-2026-00582

🎯 Affected products4

  • go/github.com/mattermost/mattermost/server/v8:>= 11.5.0, < 11.5.2
  • go/github.com/mattermost/mattermost/server/v8:>= 10.11.0, < 10.11.14
  • go/github.com/mattermost/mattermost/server/v8:< 8.0.0-20260325160634-e738016c5920
  • go/github.com/mattermost/mattermost-server:< 5.3.2-0.20260325160634-e738016c5920

🔗 References (4)