Is CVE-2026-54776 being exploited?

No public exploit is currently tracked.

How severe is CVE-2026-54776?

CVE-2026-54776 has a CVSS v3 severity of MEDIUM (4.4).

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CVE-2026-54776

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.