User Impersonation Affecting symfony/security-http package, versions <5.4.52>=6.0.0-BETA1, <6.4.40>=7.0.0-BETA1, <7.4.12>=8.0.0-BETA1, <8.0.12
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- published24 May 2026
- disclosed20 May 2026
- creditClaude Mythos Preview
Introduced: 20 May 2026
NewCVE-2026-45063 (opens in a new tab)How to fix?
Upgrade symfony/security-http to version 5.4.52, 6.4.40, 7.4.12, 8.0.12 or higher.
Overview
symfony/security-http is a provides an infrastructure for sophisticated authorization systems, which makes it possible to easily separate the actual authorization logic from so called user providers that hold the users credentials.
Affected versions of this package are vulnerable to User Impersonation via user identifier extraction in X509Authenticator. An attacker who can obtain a certificate from a trusted CA can impersonate arbitrary users by obtaining a trusted client certificate whose Subject DN contains a crafted CN value embedding emailAddress=victim@target, as the authenticator uses an unanchored regex that matches emailAddress= anywhere in the DN string during mTLS authentication.