What’s Vulnerable › Vulnerabilities

CVE-2026-47838: Unauthorized User Impersonation when Using X.509 Client Certificates

• Severity: high (CVSS 8.1 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.1% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-06-09 · updated 2026-07-23
• Weakness: CWE-287

Description

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. Affected versions: Spring Security 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.

Affected products

• Spring Security: before 5.7.25; from 5.8.0 before 5.8.27; from 6.3.0 before 6.3.18; from 6.4.0 before 6.4.18; from 6.5.0 before 6.5.11 — fixed in 5.7.25, 5.8.27, 6.3.18, 6.4.18, 6.5.11
• Spring Security: from 5.7.0 before 5.7.25; from 5.8.0 before 5.8.27; from 6.3.0 before 6.3.18; from 6.4.0 before 6.4.18; from 6.5.0 before 6.5.10.2 — fixed in 5.7.25, 5.8.27, 6.3.18, 6.4.18, 6.5.10.2

How to fix

Upgrade to a fixed version: Spring Security 5.7.25, 5.8.27, 6.3.18, 6.4.18; Spring Security 5.7.25, 5.8.27, 6.3.18, 6.4.18. Check the vendor advisory for mitigations.

References

• https://spring.io/security/cve-2026-47838

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