CVE-2026-54784: CoreWCF: SPNEGO SecurityContextToken proof key wrapped without confidentiality

June 19, 2026

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.

References

github.com/CoreWCF/CoreWCF/security/advisories/GHSA-2288-8h3r-cqgg
github.com/advisories/GHSA-2288-8h3r-cqgg
nvd.nist.gov/vuln/detail/CVE-2026-54784

Code Behaviors & Features

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