CVE-2026-54783 in CoreWCF
Summary
by MITRE • 07/09/2026
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.
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Analysis
by VulDB Data Team • 07/09/2026
This vulnerability affects CoreWCF implementations that handle WS-Security signed SOAP messages, specifically impacting the signature verification process during message processing. The flaw exists in how the framework validates that digital signatures within ds:Signature elements properly cover the intended Security header targets. When an attacker captures a validly signed SOAP envelope, they can replay this message to invoke arbitrary service operations while maintaining the authenticated principal context of the original requester. This represents a critical authentication bypass vulnerability where the system fails to verify that signatures are bound to the correct security contexts, allowing for unauthorized operation execution under legitimate user credentials.
The technical implementation flaw stems from insufficient validation of signature target binding within the WS-Security processing pipeline. CoreWCF's signature verification logic does not properly enforce that the ds:Signature element references the correct Security header elements it should protect, creating a gap where replayed messages can successfully authenticate despite potentially targeting different operations than originally intended. This weakness allows attackers to leverage captured signed messages to perform unauthorized service calls while maintaining the original principal's authorization context and permissions.
The operational impact of this vulnerability is severe as it enables authenticated privilege escalation and arbitrary service invocation attacks. An attacker with access to a single captured signed SOAP message can repeatedly execute service operations that require authentication, effectively granting them persistent access to the victim's authorized privileges without needing additional credentials or authentication mechanisms. This creates a significant risk for services that rely on WS-Security for authentication and authorization, particularly in enterprise environments where service operations may have elevated privileges or access to sensitive data.
This vulnerability maps to CWE-347, which addresses improper verification of cryptographic signatures, and aligns with ATT&CK technique T1550.001 for use of stolen credentials through legitimate network protocols. The flaw represents a failure in the authentication validation process where the system accepts replayed signatures without proper target validation. Organizations should immediately upgrade to CoreWCF versions 1.8.1 or 1.9.1 to address this issue, implement additional monitoring for suspicious replay patterns, and consider implementing message deduplication mechanisms to prevent unauthorized reuse of captured signed messages. Security teams should also review their WS-Security implementations to ensure proper signature target validation is enforced across all service endpoints.
The vulnerability demonstrates how cryptographic verification can be bypassed when proper signature binding validation is omitted from security processing pipelines. This particular flaw underscores the importance of comprehensive signature verification that not only validates cryptographic integrity but also ensures that signatures are correctly bound to their intended security contexts. The fix implemented in versions 1.8.1 and 1.9.1 likely includes enhanced validation logic to verify that ds:Signature elements properly reference the expected Security header targets, preventing replay attacks that exploit signature binding weaknesses in the WS-Security implementation.