CVE-2026-54776: CoreWCF: Unix Domain Socket PosixIdentity transport accepts connections that skip the security upgrade

June 19, 2026

A CoreWCF service hosted on Unix Domain Sockets with the PosixIdentity client credential type (UnixDomainSocketBinding with Security.Mode = TransportCredentialOnly and Security.Transport.ClientCredentialType = PosixIdentity) does not require the client to perform the application/unixposix stream upgrade before dispatching messages.

References

github.com/CoreWCF/CoreWCF/security/advisories/GHSA-wjpq-6766-7f5j
github.com/advisories/GHSA-wjpq-6766-7f5j
nvd.nist.gov/vuln/detail/CVE-2026-54776

Code Behaviors & Features

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