CoreWCF: Unix Domain Socket PosixIdentity transport accepts connections that skip the security upgrade
Impact
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.
Patches
Fixed in CoreWCF v1.8.1 and v1.9.1
Workarounds
Restrict filesystem access to the UDS socket file using owner/group/mode (e.g. chmod 0660 plus a dedicated group) so that only the POSIX users who are already authorized to invoke the service can connect at all. This makes the missing-upgrade behaviour equivalent to the operating system’s filesystem permissions instead of relying on framing-layer identity checks. Avoid relying on ServiceSecurityContext.PrimaryIdentity for authorization decisions, or back it up with an authentication-required authorization policy that rejects anonymous principals.
Affected software
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| Platform | Package | Vulnerable versions | Fixed in |
|---|---|---|---|
| .NET (NuGet) | CoreWCF.UnixDomainSocket | < 1.8.1, >= 1.9.0, < 1.9.1 | 1.8.1, 1.9.1 |
References
- CVSS vector
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N- Weakness (CWE)
CWE-306- Platform
- .NET (NuGet)
- Package
CoreWCF.UnixDomainSocket- Disclosed
- 19.06.2026
- Updated
- 11.10.2026 11:23
Sources and licenses
OSV / GitHub Advisory Database - GHSA-wjpq-6766-7f5j - CC BY 4.0
Vulnerability history: CoreWCF.UnixDomainSocket
All published vulnerabilities of this package (.NET (NuGet)), newest first. Shows whether this is a one-off slip or a package that needs watching.
- Total entries
- 2
- First → latest
- 06.2026 06.2026
- Without a fix
- 0
- Exploited in attacks
- 0
Severity breakdown
- Medium 2
Disclosures per year
- 2026: 2
-
CoreWCF: Unix Domain Socket PosixIdentity transport accepts connections that skip the security upgrade this entry
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