CoreWCF: SamlSerializer skips SignatureValue verification when SAML signing token is not an X.509 certificate
Priority LOW 34CWE-345Published · Updated
Key facts
- Attack vector
- Network
- Privileges required
- None
- User interaction
- None
- Attack complexity
- High
- Impact type
- Security bypass
- Confidentiality · integrity · availability
- High · High · None
- Fix status
- Fixed
Attack profile from CVSS 3.1 · CNA. Fix status from CNA and GitHub. Impact type from CWE-345.
Summary
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, SamlSerializer skips final SignatureValue verification when a CoreWCF service validates SAML tokens using a non-X.509 signing token, allowing an attacker to reference a non-X.509 SecurityToken key identifier and bypass assertion signature verification. This issue is fixed in versions 1.8.1 and 1.9.1.
Why it matters now
Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00203 10th percentileScored 2026-11-07
Fix Fixed CoreWCF (CoreWCF): 1.9.1, 1.8.1CoreWCF.Primitives (NuGet): 1.8.1, 1.9.1
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- None
- Automatable
- No
- Technical impact
- Total
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| CoreWCF | CoreWCF | 1.9.0 to before 1.9.1; before 1.8.1 | 1.9.1, 1.8.1 | Patch available | CNA |
| — | CoreWCF.Primitives (NuGet) | before 1.8.1 | 1.8.1 | Patch available | GHSA-rpj7-hr7h-w6p9 |
| — | CoreWCF.Primitives (NuGet) | 1.9.0 to before 1.9.1 | 1.9.1 | Patch available | GHSA-rpj7-hr7h-w6p9 |
- CoreWCF VendorCoreWCF Affected 1.9.0 to before 1.9.1; before 1.8.1 Fixed in 1.9.1, 1.8.1 Patch available CNA
- CoreWCF.Primitives (NuGet) Vendor— Affected before 1.8.1 Fixed in 1.8.1 Patch available GHSA-rpj7-hr7h-w6p9
- CoreWCF.Primitives (NuGet) Vendor— Affected 1.9.0 to before 1.9.1 Fixed in 1.9.1 Patch available GHSA-rpj7-hr7h-w6p9
Remediation
- Fix · CNA CoreWCF (CoreWCF) Fixed in 1.9.1, 1.8.1
- Fix · GHSA-rpj7-hr7h-w6p9 CoreWCF.Primitives (NuGet) Fixed in 1.8.1 Advisory →
- Fix · GHSA-rpj7-hr7h-w6p9 CoreWCF.Primitives (NuGet) Fixed in 1.9.1 Advisory →
Timeline
- 2026-10-02 Threatist record created from CVE-2026-54774
- 2026-10-03 Alias added: GHSA-rpj7-hr7h-w6p9
References
Other 7
- https://github.com/CoreWCF/CoreWCF/security/advisories/GHSA-rpj7-hr7h-w6p9
- https://github.com/CoreWCF/CoreWCF/commit/65d09022749854ba943e376aefb958dec05b00d8
- https://github.com/CoreWCF/CoreWCF/commit/b914495ce63c44924664643b60a262e7595081a4
- https://github.com/CoreWCF/CoreWCF/commit/e7454132876ecc7e2cf80e541a44376eeb54979b
- https://github.com/CoreWCF/CoreWCF/releases/tag/v1.8.1
- https://github.com/CoreWCF/CoreWCF/releases/tag/v1.9.1
- https://github.com/CoreWCF/CoreWCF
More CoreWCF vulnerabilities
- TI-2026-39588 CoreWCF: Authentication bypass in CoreWCF SAML 1.1 / 2.0 token signature validation CVSS 3.1CRITICAL 10.0
- TI-2026-39578 CoreWCF: Pre-authentication infinite-loop CPU exhaustion in CoreWCF net.tcp / net.pipe / net.uds framing handshake CVSS 3.1HIGH 7.5
- TI-2024-18811 CoreWCF NetFraming based services can leave connections open when they should be closed CVSS 3.1HIGH 7.5
- TI-2026-39590 CoreWCF: SPNEGO SecurityContextToken proof key wrapped without confidentiality CVSS 3.1HIGH 7.4
- TI-2026-39589 Authentication bypass by capture-replay in CoreWCF CVSS 3.1HIGH 7.4
- TI-2026-39587 CoreWCF: SAML SubjectConfirmation methods and holder-of-key proof keys are not enforced CVSS 3.1HIGH 7.4
Sources
- CVE-2026-54774 · CVE Program
- CVE-2026-54774 · NVD
- FIRST EPSS
- GHSA-rpj7-hr7h-w6p9 · GitHub Advisory Database · CC BY 4.0
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