CVE-2026-19600 PUBLISHED

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

Assigner: Mattermost
Reserved: 12.08.2026 Published: 16.10.2026 Updated: 16.10.2026

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

Metrics

CVSS 3.1

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

Attack Vector	Network	Scope	Unchanged
Attack Complexity	Low	Confidentiality Impact	High
Privileges Required	High	Integrity Impact	None
User Interaction	Required	Availability Impact	None

CVSS 3.1

Product Status

Vendor	Mattermost
Product	Mattermost
Versions	Default: unaffected affected from 11.9.0 to 11.9.1 (incl.) affected from 11.8.0 to 11.8.5 (incl.) affected from 11.7.0 to 11.7.10 (incl.) affected from 11.10.0 to 11.10.1 (incl.) Version 11.11.0 is unaffected Version 11.9.2 is unaffected Version 11.8.6 is unaffected Version 11.7.11 is unaffected Version 11.10.2 is unaffected

Solutions

Update Mattermost to versions 11.11.0, 11.9.2, 11.8.6, 11.7.11, 11.10.2 or higher.

Credits

CERT PL finder

References

MMSA-2026-00763

Problem Types

CWE-532: Insertion of Sensitive Information into Log Files CWE