Is CVE-2026-54783 being exploited?

No public exploit is currently tracked.

How severe is CVE-2026-54783?

CVE-2026-54783 has a CVSS v3 severity of HIGH (7.4).

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CVE-2026-54783

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, CoreWCF WS-Security endorsing and supporting signature verification does not ensure the selected ds:Signature covers the expected Security header target, allowing an attacker with one captured signed SOAP envelope to replay arbitrary service operations as the victim principal. This issue is fixed in versions 1.8.1 and 1.9.1.