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
Threat Intelligence
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
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- published24 May 2026
- disclosed20 May 2026
- creditClaude Mythos Preview
Introduced: 20 May 2026
CVE-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.