CVE-2026-54776

Name of the Vulnerable Software and Affected Versions CoreWCF versions prior to 1.8.1 CoreWCF versions prior to 1.9.1

Description A CoreWCF service hosted on Unix Domain Sockets using PosixIdentity client credentials may accept connections that bypass the application/unixposix stream upgrade before dispatching messages. This allows the bypass of framing-layer identity checks within the UnixPosixIdentitySecurityUpgradeProvider when the UnixDomainSocketBinding is configured with Security.Mode set to TransportCredentialOnly and Security.Transport.ClientCredentialType set to PosixIdentity.

Recommendations Update to version 1.8.1. Update to version 1.9.1. Restrict filesystem access to the Unix Domain Socket socket file using owner, group, and mode (e.g., chmod 0660 with a dedicated group) to ensure only authorized POSIX users can connect. Avoid using ServiceSecurityContext.PrimaryIdentity for authorization decisions or implement an authentication-required authorization policy that rejects anonymous principals.