CVE-2017-18909: Mattermost Server SAML implementation does not require encryption or signature verification as default

May 24, 2022 (updated February 6, 2026)

An issue was discovered in Mattermost Server before 3.9.0 when SAML is used. Encryption and signature verification are not mandatory.

References

github.com/advisories/GHSA-r6j5-fqx9-7qv9
github.com/mattermost/mattermost
github.com/mattermost/mattermost/commit/4f074fed0d653a28779ac586e418341232d43e95
mattermost.com/security-updates
nvd.nist.gov/vuln/detail/CVE-2017-18909

Code Behaviors & Features

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