CVE-2025-13821

MEDIUM5.7EPSS 0.04%

Mattermost fails to sanitize sensitive data in WebSocket messages

Published: 2/16/2026Modified: 4/1/2026

Description

Mattermost versions 11.1.x <= 11.1.2, 10.11.x <= 10.11.9, 11.2.x <= 11.2.1 fail to sanitize sensitive data in WebSocket messages which allows authenticated users to exfiltrate password hashes and MFA secrets via profile nickname updates or email verification events. Mattermost Advisory ID: MMSA-2025-00560

Affected packages (6)

Go/github.com/mattermost/mattermost-server>= 11.1.0
Go/github.com/mattermost/mattermost-serverfrom 0
Go/github.com/mattermost/mattermost-server/v5from 0
Go/github.com/mattermost/mattermost-server/v6from 0
Go/github.com/mattermost/mattermost/server/v8from 0, < 8.0.0-20251210191531-cd17b61de41b
Go/github.com/mattermost/mattermost/server/v8from 0, < 8.0.0-20251210191531-cd17b61de41b

CVSS scores

Source	Version	Severity	Vector
osv	CVSS 3.1	MEDIUM5.7	CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:N/A:N

References (5)

ADVISORYhttps://github.com/advisories/GHSA-pp9j-pf5c-659x
ADVISORYhttps://nvd.nist.gov/vuln/detail/CVE-2025-13821
PATCHhttps://github.com/mattermost/mattermost
WEBhttps://github.com/mattermost/mattermost/commit/cd17b61de41bf0a49b524bb91ce0bbe859e5a100
WEBhttps://mattermost.com/security-updates