CVE-2026-19600

Mattermost logs plaintext authentication tokens in debug-level server logs on failed auth attempts

State: Published
Severity: 4.5 Medium
Published: Oct 16, 2026
Updated: Oct 16, 2026
Reserved: Aug 12, 2026

Description

Mattermost versions 11.9.x <= 11.9.1, 11.8.x <= 11.8.5, 11.7.x <= 11.7.10, 11.10.x <= 11.10.1 fail to sanitize authentication tokens before writing them to server log entries, which allows an attacker with access to server logs to obtain valid session tokens or OAuth access tokens and impersonate authenticated users via the debug-level Mattermost server log.. Mattermost Advisory ID: MMSA-2026-00763

Scores

CVSS	Score	Vector	Source
3.1	4.5 Medium	CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:U/C:H/I:N/A:N	Mattermost

Weaknesses

CWE-532 Insertion of Sensitive Information into Log Files

Affected Products

Product	Versions
MattermostMattermost	11.9.0 through 11.9.1Affected 11.8.0 through 11.8.5Affected 11.7.0 through 11.7.10Affected 11.10.0 through 11.10.1Affected 11.11.0Not affected 11.9.2Not affected 11.8.6Not affected 11.7.11Not affected 11.10.2Not affected

References

MMSA-2026-00763vendor-advisory

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