GitHub Advisoryadvisory · Go

GHSA-vqp5-2mrp-qqxg Mattermost doesn't validate the Host header when constructing response URLs for custom slash command

LOW Published 2026-05-18 Modified 2026-06-01 Official page ↗
Aliases
CVE-2026-6333
Ecosystem
Go
Packages
github.com/mattermost/mattermost/server/v8, github.com/mattermost/mattermost-server
Severity
Low
CVSS vector
CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:N/I:L/A:N
Weaknesses
CWE-918
Reviewed
2026-06-01

Affected packages

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

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

Related

Alias · CVE (1)

  • CVE-2026-6333 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… vulnerability

Weakness · CWE (1)

  • CWE-918 Server-Side Request Forgery weakness

References