Authentication bypass by capture-replay in CoreWCF
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-294.
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, 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.
Why it matters now
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-gqv6-pwcg-87r8 |
| — | CoreWCF.Primitives (NuGet) | 1.9.0 to before 1.9.1 | 1.9.1 | Patch available | GHSA-gqv6-pwcg-87r8 |
- 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-gqv6-pwcg-87r8
- CoreWCF.Primitives (NuGet) Vendor— Affected 1.9.0 to before 1.9.1 Fixed in 1.9.1 Patch available GHSA-gqv6-pwcg-87r8
Remediation
- Fix · CNA CoreWCF (CoreWCF) Fixed in 1.9.1, 1.8.1
- Fix · GHSA-gqv6-pwcg-87r8 CoreWCF.Primitives (NuGet) Fixed in 1.8.1 Advisory →
- Fix · GHSA-gqv6-pwcg-87r8 CoreWCF.Primitives (NuGet) Fixed in 1.9.1 Advisory →
Timeline
- 2026-10-02 Threatist record created from CVE-2026-54783
- 2026-10-03 Alias added: GHSA-gqv6-pwcg-87r8
References
Other 7
- https://github.com/CoreWCF/CoreWCF/security/advisories/GHSA-gqv6-pwcg-87r8
- https://github.com/CoreWCF/CoreWCF/commit/0589692d4b9a41d21b34ac48281e95f6df7f4ce5
- https://github.com/CoreWCF/CoreWCF/commit/30aef805270976c42477e3f2a05f4e563d86e247
- https://github.com/CoreWCF/CoreWCF/commit/4618f24165ad018ad3ed2636bf8c3bc87d2a3be2
- 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-2026-39587 CoreWCF: SAML SubjectConfirmation methods and holder-of-key proof keys are not enforced CVSS 3.1HIGH 7.4
- TI-2026-39580 CoreWCF: SamlSerializer skips SignatureValue verification when SAML signing token is not an X.509 certificate CVSS 3.1HIGH 7.4
Sources
- CVE-2026-54783 · CVE Program
- CVE-2026-54783 · NVD
- FIRST EPSS
- GHSA-gqv6-pwcg-87r8 · GitHub Advisory Database · CC BY 4.0
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