🛡️ CVE-2026-54776 — corewcf.unixdomainsocket
Description
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.
How this vulnerability can be exploited
This issue can be reached with local access to the system, attack complexity is low, an attacker needs low-level privileges on the target. No user interaction is required. The scope is unchanged, so the impact stays within the vulnerable component. Rated impact: confidentiality low, integrity low, availability none.
Weakness class
CVE-2026-54776 is classified as CWE-306: Missing Authentication for Critical Function. A sensitive function can be reached without authenticating at all.
Affected software
CVE-2026-54776 is recorded against 2 packages.
- corewcf.unixdomainsocket (from 1.9.0 up to 1.9.1)
- unknown
Timeline and source
Published on 19 June 2026. No public exploit is currently recorded for this entry. Record sourced from NVD.
References
Details
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N
Affected Packages
| Software | From version | Fixed in |
|---|---|---|
| corewcf.unixdomainsocket | 1.9.0 | 1.9.1 |
| unknown | — | — |
References
Similar Threats
- Medium CVE-2026-54778
More CVE 2026 advisories
Browse all of CVE 2026 in the advisory index.
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