CVE-2026-2457

Description

Mattermost versions 11.3.x <= 11.3.0, 11.2.x <= 11.2.2, 10.11.x <= 10.11.10 fail to sanitize client-supplied post metadata which allows an authenticated attacker to spoof permalink embeds impersonating other users via crafted PUT requests to the post update API endpoint. Mattermost Advisory ID: MMSA-2025-00569

Affected packages (6)

• Go/github.com/mattermost/mattermost-serverfrom 0, < 5.3.2-0.20260123211116-9efe617be8b8
• Go/github.com/mattermost/mattermost-server>= 10.11.0-rc1+incompatible, < 10.11.11+incompatible, >= 11.2.0-rc1+incompatible, < 11.2.3+incompatible, >= 11.3.0-rc1+incompatible, < 11.3.1+incompatible
• Go/github.com/mattermost/mattermost-server/v5from 0
• Go/github.com/mattermost/mattermost-server/v6from 0
• Go/github.com/mattermost/mattermost/server/v8from 0, < 8.0.0-20260123211116-9efe617be8b8
• Go/github.com/mattermost/mattermost/server/v8from 0, < 8.0.0-20260123211116-9efe617be8b8

CVSS scores

References (5)

• ADVISORYhttps://github.com/advisories/GHSA-ph22-fw5m-w2q9
• ADVISORYhttps://nvd.nist.gov/vuln/detail/CVE-2026-2457
• PATCHhttps://github.com/mattermost/mattermost
• WEBhttps://github.com/mattermost/mattermost/commit/9efe617be8b8f1d036e12721e8e73b69a543ed34
• WEBhttps://mattermost.com/security-updates