CVE-2026-47838: Spring Security Vulnerable to Unauthorized User Impersonation when Using X.509 Client Certificates

June 10, 2026 (updated June 30, 2026)

In Spring Security Web, SubjectDnX509PrincipalExtractor does not correctly handle certain malformed X.509 certificate CN values, which can lead to reading the wrong value for the username. In a carefully crafted certificate, this can lead to an attacker impersonating another user.

SubjectDnX509PrincipalExtractor is deprecated by this CVE and replaced with SubjectX500PrincipalExtractor. As part of updating, you should also migrate to SubjectX500PrincipalExtractor.

Affected versions: Spring Security Enterprise 5.7.0 through 5.7.24; 5.8.0 through 5.8.26; 6.3.0 through 6.3.17; 6.4.0 through 6.4.17; 6.5.0 through 6.5.10. OSS 6.5.0 through 6.5.10.

References

Code Behaviors & Features

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