CVE-2026-54784High· 7.4▾ TwilightCoreWCF: SPNEGO SecurityContextToken proof key wrapped without confidentiality
▾ Twilight zone — High severity, or a signal on a lesser flaw
impact 40.7 · likelihood 0.1 · exploitation 0
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Exploit-prediction probability, daily snapshots since Jul 9.
Disclosure to exploitation, from the record and what we observed since indexing it.
Disclosed via GHSA
0.2%
0.2% → 0.3%
When the proof key recovered from the RSTR can be observed by a party that is not the legitimate client, that party can impersonate the authenticated Windows principal for the lifetime of the SCT (default ~10 hours) and decrypt or forge any subsequent WS‑SecureConversation traffic that uses keys derived from the SCT.
Using security mode TransportWithMessageCredential with client credential type Windows, along with session establishment (which triggers use of WS-SecureConversation).
Fixed in CoreWCF v1.9.1
Ensure communication is protected by SSL/TLS to prevent capturing of SCT negotiation handshake.
CoreWCF.Primitives >= 1.9.0, < 1.9.1Upgrade to a patched release:
CoreWCF.Primitives 1.9.1Connected by shared product, vendor, weakness, or advisory.
CVE-2026-54773Medium· 5.9CoreWCF: WS-Security signature substitution via document-wide Signature lookup
CVE-2026-54774High· 7.4CoreWCF: SamlSerializer skips SignatureValue verification when SAML signing token is not an X.509 certificate
CVE-2026-54779Medium· 5.9CoreWCF: SAML token replay protection is inoperative
CVE-2026-54780Low· 3.7CoreWCF: WS-Security Reference DigestMethod Algorithm-Suite Bypass
CVE-2026-54781High· 7.4CoreWCF: SAML SubjectConfirmation methods and holder-of-key proof keys are not enforced
CVE-2026-54782Critical· 10.0CoreWCF: Authentication bypass in CoreWCF SAML 1.1 / 2.0 token signature validation