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CVE-2025-13821 Moderate

Mattermost fails to sanitize sensitive data in WebSocket messages in github.com/mattermost/mattermost-server

Mattermost fails to sanitize sensitive data in WebSocket messages in github.com/mattermost/mattermost-server. NOTE: The source advisory for this report contains additional versions that could not be automatically mapped to standard Go module versions. (If this is causing false-positive reports from vulnerability scanners, please suggest an edit to the report.) The additional affected modules and versions are: github.com/mattermost/mattermost-server/v5 before v5.3.2-0.20251210191531-cd17b61de41b.

Exploit probability 0.2%
Published February 23, 2026
Required by Not available
Last source change February 23, 2026

02 / AFFECTED SOFTWARE

Affected packages

Unknown Unknown

34 explicit affected versions

Go github.com/mattermost/mattermost-server
Go github.com/mattermost/mattermost/server/v8
Go github.com/mattermost/mattermost-server
Go github.com/mattermost/mattermost-server/v5
Go github.com/mattermost/mattermost-server/v6
Go github.com/mattermost/mattermost/server/v8

03 / CONNECTIONS

Connected vulnerabilities

related OPENSUSE-SU-2026:21483-1

04 / EVIDENCE

Source records

Open Source Vulnerabilities CVE-2025-13821

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

View original source
Open Source Vulnerabilities GHSA-pp9j-pf5c-659x

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

View original source
Open Source Vulnerabilities GO-2026-4524

Mattermost fails to sanitize sensitive data in WebSocket messages in github.com/mattermost/mattermost-server. NOTE: The source advisory for this report contains additional versions that could not be automatically mapped to standard Go module versions. (If this is causing false-positive reports from vulnerability scanners, please suggest an edit to the report.) The additional affected modules and versions are: github.com/mattermost/mattermost-server/v5 before v5.3.2-0.20251210191531-cd17b61de41b.

View original source

05 / REFERENCES

Further evidence