Know every vulnerabilitybefore it knows you.
DevGuard continuously monitors your dependencies and alerts you when CVEs like this one affect your stack — with real-time threat intelligence built for developers.
GHSA-ph86-p8f6-f9r2
No affected components available
Description
X509Authenticator implements client-certificate (mTLS) authentication: the web server validates the client's certificate against a trusted CA, then passes the certificate's Subject DN (Distinguished Name: a string like CN=Alice,O=Example,emailAddress=alice@example.com) to Symfony via $_SERVER['SSL_CLIENT_S_DN']. Symfony extracts the user identifier from that string.
The extraction uses an unanchored regex that matches emailAddress= anywhere in the DN string: including inside the value of a different RDN (Relative Distinguished Name: one key=value component of the DN), such as CN. An attacker who can obtain a certificate from a trusted CA with a free-text CN can smuggle emailAddress=victim@target inside the CN value and be authenticated as the victim.
Resolution
The X509Authenticator now uses a regex that anchors the match to an RDN boundary (start of string, or following a , / / separator).
The patch for this issue is available here for branch 5.4.
Credits
Symfony would like to thank Claude Mythos Preview (via Project Glasswing) for reporting the issue and providing the fix.
The vulnerability can be exploited over the network without needing physical access. It is easy for an attacker to exploit this vulnerability. An attacker does not need any special privileges or access rights. No user interaction is needed for the attacker to exploit this vulnerability.
Exploitation attempts have been detected. Elevated vigilance and prompt remediation are advised.
The exploit probability is very low. The vulnerability is unlikely to be exploited in the next 30 days.
We did not find any exploit available. Neither in GitHub repositories nor in the Exploit-Database.
Browse More
Continuously monitor your dependencies and get alerted when vulnerabilities like this one affect your stack.
Checkout DevGuard