Authentication Bypass by Spoofing in Symfony - CVE-2026-45063
Published: May 21, 2026
Vulnerability identifier: #VU132071
CSH Severity: Low
CVSS v4: 7.1 [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]
CVE-ID: CVE-2026-45063
CWE-ID: CWE-290
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
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.
Affected software
Symfony
Debian Linux
symfony (Debian package)
Debian Linux
symfony (Debian package)
How to mitigate CVE-2026-45063
Install security update from vendor's website.
Symfony - addressed in versions 5.4.52, 6.4.40, 7.4.12, 8.0.12
symfony (Debian package) - addressed in versions 5.4.53+dfsg-0+deb12u1, 6.4.41+dfsg-0+deb13u1
symfony (Debian package) - addressed in versions 5.4.53+dfsg-0+deb12u1, 6.4.41+dfsg-0+deb13u1