CoreWCF CVE-2026-54780
LOW
GHSA-4v55-cpmv-3vcm
Severity by source
AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N
Endpoint is network-reachable with no auth needed (AV:N/PR:N), but crafting a valid XMLDSig bypass demands specialized cryptographic knowledge (AC:H); only limited integrity impacted.
Primary rating from Vendor (https://github.com/CoreWCF/CoreWCF).
CVSS VectorVendor: https://github.com/CoreWCF/CoreWCF
Lifecycle Timeline
2DescriptionCVE.org
Impact
CoreWCF’s WS-Security 1.0 receive pipeline validates the SignatureMethod of an incoming ds:SignedInfo against the configured SecurityAlgorithmSuite, but does not validate the DigestMethod declared on each ds:Reference. As a result, a sender can populate ds:SignedInfo with SignatureMethod values the suite accepts (for example rsa-sha256 under Basic256Sha256) while declaring a per-reference DigestMethod the suite rejects (for example http://www.w3.org/2000/09/xmldsig#sha1). The signature is then verified where it permits SHA-1 digests, and the message is accepted.
Patches
Fixed in CoreWCF v1.8.1 and v1.9.1
Workarounds
None
AnalysisAI
WS-Security DigestMethod validation in CoreWCF's receive pipeline can be bypassed, allowing a remote sender to present XML Digital Signatures that use cryptographically weak per-reference hash algorithms (e.g., SHA-1) even when the configured SecurityAlgorithmSuite explicitly prohibits them. Affected are all CoreWCF.Primitives releases below v1.8.1 and the 1.9.0 release (pre-1.9.1). The service silently accepts these weakened signatures as policy-compliant, undermining the integrity guarantees that the algorithm suite is designed to enforce. No public exploit or CISA KEV listing exists; the vendor has released patches in v1.8.1 and v1.9.1 with no available workaround.
Technical ContextAI
CoreWCF is an open-source .NET reimplementation of Windows Communication Foundation, distributed as the nuget/CoreWCF.Primitives NuGet package. WS-Security 1.0 relies on XML Digital Signatures (XMLDSig), where a ds:SignedInfo block carries a SignatureMethod element (controlling the overall signing algorithm) and one or more ds:Reference elements, each with its own DigestMethod (controlling how each referenced element is hashed before signing). A SecurityAlgorithmSuite such as Basic256Sha256 is intended to constrain both dimensions. CoreWCF's receive pipeline validated only SignatureMethod against the configured suite, leaving DigestMethod per reference unchecked. This maps directly to CWE-327 (Use of a Broken or Risky Cryptographic Algorithm): SHA-1 is a known-deprecated digest in WS-Security contexts, and its silent acceptance constitutes use of a risky algorithm contrary to the operator's explicit security policy. The affected CPE is pkg:nuget/corewcf.primitives.
RemediationAI
Upgrade CoreWCF.Primitives to v1.8.1 if consuming the 1.8.x branch, or to v1.9.1 if consuming the 1.9.x branch, as confirmed by the vendor advisory at https://github.com/CoreWCF/CoreWCF/security/advisories/GHSA-4v55-cpmv-3vcm. These are the only vendor-released patches; both version ranges are addressed. The vendor explicitly documents no workarounds. For teams unable to patch immediately, a potential compensating control is placing an XML-aware security gateway or WS-Policy enforcement proxy in front of the CoreWCF endpoint to independently reject messages whose ds:Reference DigestMethod values fall outside the permitted suite - however, this is not a vendor-tested mitigation, adds latency and operational complexity, and may break valid clients if misconfigured. Mutual TLS at the transport layer does not mitigate this issue because the bypass occurs at the WS-Security message layer regardless of transport security.
Same technique Information Disclosure
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External POC / Exploit Code
Leaving vuln.today