GitHub Advisoryadvisory · Go

GHSA-gqv7-j2j8-qmwq Mattermost fails to canonicalize IPv4-mapped IPv6 addresses before reserved IP validation

MEDIUM Published 2026-03-16 Modified 2026-03-18 Official page ↗
Aliases
CVE-2026-2455
Ecosystem
Go
Packages
github.com/mattermost/mattermost/server/v8, github.com/mattermost/mattermost-server
Severity
Moderate
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N
Weaknesses
CWE-918
Reviewed
2026-03-18

Affected packages

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

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

Related

Alias · CVE (1)

  • CVE-2026-2455 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… vulnerability

Weakness · CWE (1)

  • CWE-918 Server-Side Request Forgery weakness

References