CoreWCF Unix Domain Socket Identity Bypass Vulnerability

Publication date: 2026-07-08

Last updated on: 2026-07-08

Assigner: GitHub, Inc.

Description

CoreWCF is a port of the service side of Windows Communication Foundation (WCF) to .NET Core. Prior to 1.8.1 and 1.9.1, a CoreWCF service hosted on Unix Domain Sockets with PosixIdentity client credentials can accept connections that skip the application/unixposix stream upgrade before dispatching messages, bypassing framing-layer identity checks in UnixPosixIdentitySecurityUpgradeProvider. This issue is fixed in versions 1.8.1 and 1.9.1.

CVSS Scores

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Meta Information

Published

2026-07-08

Last Modified

2026-07-08

Generated

2026-07-09

AI Q&A

2026-07-09

EPSS Evaluated

N/A

NVD

CVE-2026-54776

Affected Vendors & Products

Vendor	Product	Version / Range
corewcf	corewcf	to 1.8.1 (inc)
corewcf	corewcf	to 1.9.1 (inc)

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-306	The product does not perform any authentication for functionality that requires a provable user identity or consumes a significant amount of resources.

Attack-Flow Graph

Executive Summary

This vulnerability exists in CoreWCF, a port of the Windows Communication Foundation service side to .NET Core. Before versions 1.8.1 and 1.9.1, a CoreWCF service hosted on Unix Domain Sockets using PosixIdentity client credentials could accept connections that bypass the required application/unixposix stream upgrade. This means that the framing-layer identity checks performed by the UnixPosixIdentitySecurityUpgradeProvider could be skipped, potentially allowing unauthorized connections.

Impact Analysis

The vulnerability allows connections to bypass identity checks at the framing layer, which could lead to unauthorized access or impersonation of clients. This can compromise the integrity and confidentiality of communications between services and clients, potentially allowing attackers to send or receive messages without proper authentication.

Mitigation Strategies

To mitigate this vulnerability, you should upgrade CoreWCF to version 1.8.1 or 1.9.1, where the issue has been fixed.

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