Summary
CoreWCF: SamlSerializer skips SignatureValue verification when SAML signing token is not an X.509 certificate
Preconditions
The service is configured to authenticate using SAML tokens and an out of band token resolver (commonly the IssuerTokenResolver of IssuedTokenServiceCredential) holds a non-X.509 SecurityToken whose key identifier the attacker can reference in the assertion’s <KeyInfo> - for example a BinarySecretSecurityToken representing the symmetric proof key issued by a WS-Trust symmetric-key holder-of-key STS.
Workarounds
None
Impact
When a service is configured to validate SAML tokens using a method other than X.509 certificate signing, the final signature verification is skipped.
CVE-2026-54774 has a CVSS score of 7.4 (High). The vector is network-reachable, no privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (1.8.1, 1.9.1); upgrading removes the vulnerable code path.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
Already deployed Kodem?
See it in your environmentNew to Kodem? Get a demo →Remediation advice
Fixed in CoreWCF v1.8.1 and v1.9.1
Frequently Asked Questions
- What is CVE-2026-54774? CVE-2026-54774 is a high-severity security vulnerability in CoreWCF.Primitives (nuget), affecting versions < 1.8.1. It is fixed in 1.8.1, 1.9.1.
- How severe is CVE-2026-54774? CVE-2026-54774 has a CVSS score of 7.4 (High). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
- Which versions of CoreWCF.Primitives are affected by CVE-2026-54774? CoreWCF.Primitives (nuget) versions < 1.8.1 is affected.
- Is there a fix for CVE-2026-54774? Yes. CVE-2026-54774 is fixed in 1.8.1, 1.9.1. Upgrade to this version or later.
- Is CVE-2026-54774 exploitable, and should I be worried? Whether CVE-2026-54774 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether CVE-2026-54774 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
- How do I fix CVE-2026-54774?
- Upgrade
CoreWCF.Primitivesto 1.8.1 or later - Upgrade
CoreWCF.Primitivesto 1.9.1 or later
- Upgrade