GHSA-gqv7-j2j8-qmwqMediumCVSS 4.3

Mattermost fails to canonicalize IPv4-mapped IPv6 addresses before reserved IP validation

Published
March 16, 2026
Last Modified
March 18, 2026

🔗 CVE IDs covered (1)

CVE-2026-2455 →

📋 Description

Mattermost versions 11.3.x <= 11.3.0, 11.2.x <= 11.2.2, 10.11.x <= 10.11.10 fail to canonicalize IPv4-mapped IPv6 addresses before reserved IP validation which allows an attacker to perform SSRF attacks against internal services via IPv4-mapped IPv6 literals (e.g., [::ffff:127.0.0.1]).. Mattermost Advisory ID: MMSA-2026-00585

🎯 Affected products5

  • go/github.com/mattermost/mattermost/server/v8:< 8.0.0-20260129133647-5d787969c2d5
  • go/github.com/mattermost/mattermost-server:< 5.3.2-0.20260129133647-5d787969c2d5
  • go/github.com/mattermost/mattermost-server:>= 10.11.0-rc1, < 10.11.11
  • go/github.com/mattermost/mattermost-server:>= 11.2.0-rc1, < 11.2.3
  • go/github.com/mattermost/mattermost-server:>= 11.3.0-rc1, < 11.3.1

🔗 References (4)