Mattermost Server has intermittent Authorization bypass for resource-owners

GHSA-gg42-mwr6-p82c · CVE-2017-18894 · GO-2026-4297

Published May 24, 2022 · Modified Feb 3, 2026

Description

An issue was discovered in Mattermost Server before 4.2.0, 4.1.1, and 4.0.5, when used as an OAuth 2.0 service provider. Resource-owner authorization can be intermittently bypassed, allowing account takeover.

References

ADVISORY https://nvd.nist.gov/vuln/detail/CVE-2017-18894
PACKAGE https://github.com/mattermost/mattermost
WEB https://mattermost.com/security-updates

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