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Spring Security Vulnerable to Unauthorized User Impersonation when Using X.509 Client Certificates

Moderate severity GitHub Reviewed Published Jun 10, 2026 to the GitHub Advisory Database • Updated Jun 30, 2026

Package

maven org.springframework.security:spring-security-web (Maven)

Affected versions

>= 6.5.0, <= 6.5.10
>= 6.4.0, <= 6.4.13
>= 6.0.0, <= 6.3.10
>= 5.8.0, <= 5.8.16
<= 5.7.14

Patched versions

6.5.11

Description

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

Published by the National Vulnerability Database Jun 10, 2026
Published to the GitHub Advisory Database Jun 10, 2026
Reviewed Jun 30, 2026
Last updated Jun 30, 2026

Severity

Moderate

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

Attack vector
Network
Attack complexity
High
Privileges required
Low
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
None

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:N

EPSS score

Exploit Prediction Scoring System (EPSS)

This score estimates the probability of this vulnerability being exploited within the next 30 days. Data provided by FIRST.
(3rd percentile)

Weaknesses

Improper Authentication

When an actor claims to have a given identity, the product does not prove or insufficiently proves that the claim is correct. Learn more on MITRE.

CVE ID

CVE-2026-47838

GHSA ID

GHSA-293q-567p-wmwq

Source code

spring-projects/spring-security

Credits

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