Vulnerability in CoreWCF.Primitives (CVE-2026-54784)
Summary
Vulnerability in CoreWCF.Primitives (CVE-2026-54784). Confidential information can be exposed externally. Mitigation: upgrade to 1.9.1 or later.
Original description
The description as published by the source.
CoreWCF is a port of the service side of Windows Communication Foundation (WCF) to .NET Core. In version 1.9.0, CoreWCF SPNEGO SecurityContextToken negotiation can expose the proof key recovered from the RSTR when TransportWithMessageCredential with Windows client credentials and session establishment are used, allowing an observer to impersonate the authenticated Windows principal and decrypt or forge WS-SecureConversation traffic. This issue is fixed in version 1.9.1.
Source: GitHub Security Advisories (Global) NVD GitHub Advisory
Auto-generated summary
Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.
A vulnerability tracked as CVE-2026-54784 has been found in CoreWCF.Primitives.
Confidential information can be exposed externally. CVSS score: 7.4/10.
What to do: upgrade CoreWCF.Primitives to 1.9.1 or later.
If unsure, ask your IT team or search "CoreWCF.Primitives CVE-2026-54784" on the vendor's site.
CVE-2026-54784 (CoreWCF.Primitives) — CWE-311 / CVSS v3 7.4
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
Patched: 1.9.1 — apply immediately
Workaround: Ensure communication is protected by SSL/TLS to prevent capturing of SCT negotiation handshake.
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.
A vulnerability (CWE-311) exists in CoreWCF.Primitives.
Check the vendor advisory for the affected versions of CoreWCF.Primitives.
Severity: High (CVSS 7.4/10). Confidential information can be exposed externally.
Update to 1.9.1.
Workaround: Ensure communication is protected by SSL/TLS to prevent capturing of SCT negotiation handshake.
Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Run grep -r 'CoreWCF.Primitives' . against your dependency files (package-lock.json, requirements.txt, go.sum) to find affected services.
Response actions
Concrete steps and command examples for SOC/SRE teams to execute in order
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1Identify exposure identify
grep -r 'CoreWCF.Primitives' . | grep -v node_modulesリポジトリと本番環境の依存ファイル (package-lock.json / requirements.txt / go.sum / Gemfile.lock 等) で
CoreWCF.Primitivesを grep し、稼働しているサービス・バージョンを把握する。 -
2Apply temporary workaround mitigate
Ensure communication is protected by SSL/TLS to prevent capturing of SCT negotiation handshake.パッチが適用されるまでの応急処置として、Ensure communication is protected by SSL/TLS to prevent capturing of SCT negotiation handshake. を実施。回避策の副作用 (機能低下) を確認した上で。
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3Apply patch patch
Upgrade CoreWCF.Primitives to 1.9.1ステージング環境で 1.9.1 に上げて回帰テスト → 本番反映。回帰テストはアプリの主要ハッピーパスを含めること。
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4Post-deployment verification verify
Confirm patched version is live in productionパッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番ではアクセスログ・WAF でアラート再発が無いか継続監視。
Affected packages
References
- advisory github.com
- advisory github.com
- advisory nvd.nist.gov
- package github.com
- patch github.com
- patch github.com
- web github.com
- web github.com