CVE-2017-18894: Mattermost Server has intermittent Authorization bypass for resource-owners

May 24, 2022 (updated January 12, 2026)

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

github.com/advisories/GHSA-gg42-mwr6-p82c
github.com/mattermost/mattermost
mattermost.com/security-updates
nvd.nist.gov/vuln/detail/CVE-2017-18894

Code Behaviors & Features

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