Authentication Bypass by Spoofing in Symfony - CVE-2026-45063
Published: May 21, 2026
Vulnerability identifier: #VU132071
CSH Severity: Low
CVSS v4.0: CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:L/VI:H/VA:N/SC:N/SI:N/SA:N/E:U/U:Clear
CVE-ID: CVE-2026-45063
CWE-ID: CWE-290
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vendor: SensioLabs
Affected software:
Symfony
Symfony
Detailed vulnerability description
The vulnerability allows a remote user to spoof identities and bypass authentication.
The vulnerability exists due to improper authentication in X509Authenticator when extracting the user identifier from the Subject DN provided in $_SERVER['SSL_CLIENT_S_DN']. A remote user can obtain a certificate with a crafted CN value containing an embedded emailAddress field to spoof identities and bypass authentication.
The issue affects client-certificate authentication flows where the certificate is issued by a trusted CA and the CN field can contain free-text content.
How to mitigate CVE-2026-45063
Install security update from vendor's website.