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CVE-2026-54776 — Vulnerability in CoreWCF.UnixDomainSocket — CVE...

MEDIUM

CoreWCF: Unix Domain Socket PosixIdentity transport accepts connections that skip the security upgrade

Published June 19, 2026Updated June 19, 2026Source: osv

Summary

### 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.

Advisory Timeline

  • First published June 19, 2026 (115 days ago).
  • Last revised June 19, 2026 — 0 days after initial publication.

Remediation

Upgrade to the fixed version using your package manager.

NuGet
Update CoreWCF.UnixDomainSocket to 1.9.1 or later
dotnet add package CoreWCF.UnixDomainSocket --version 1.9.1
NuGet
Update CoreWCF.UnixDomainSocket to 1.8.1 or later
dotnet add package CoreWCF.UnixDomainSocket --version 1.8.1

After upgrading, run your dependency scanner again to confirm the vulnerability is resolved.

Affected Packages (2)

Affects 1 ecosystem: nuget (1).

PackageEcosystemAffectedFixed In
CoreWCF.UnixDomainSocket
nuget
1.9.01.9.1
CoreWCF.UnixDomainSocket
nuget
1.5.0, 1.5.0-preview1, 1.5.1, 1.5.2 (+3 more)1.8.1

Vulnerability Classification

Common Weakness Enumeration (CWE) identifiers for this vulnerability type.

CVSS Score Breakdown

What the CVSS (Common Vulnerability Scoring System) 4.4 score means for each attack dimension.

Attack Vector
Local
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
Low
Integrity
Low
Availability
None

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N

References

Frequently Asked Questions

What is CVE-2026-54776?
CoreWCF: Unix Domain Socket PosixIdentity transport accepts connections that skip the security upgrade This vulnerability has been assigned a severity rating of MEDIUM (CVSS score: 4.4/10).
How do I check if my project is affected by CVE-2026-54776?
CVE-2026-54776 affects CoreWCF.UnixDomainSocket. Use GeekWala's free vulnerability scanner to check your dependencies against CVE-2026-54776 and 200,000+ other known vulnerabilities.

Severity & Exploitability

CVSS Score
4.4

Exploitation requires specific conditions or has limited impact. Remediate within weeks.

Also Known As

GHSA-wjpq-6766-7f5j

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