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CVE-2026-54774— CoreWCF: SamlSerializer skips SignatureValue verification when SAML signing token is not an X.509 certificate

Quick assessment

Affected
CoreWCF CoreWCF
Exploitation
Public or AI PoC available; prioritize validation
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

CoreWCF是CoreWCF团队开源的一个开源项目,旨在为 .NET Core 和 .NET 5+ 提供 WCF(Windows Communication Foundation)的替代实现。 CoreWCF 1.8.1之前版本和1.9.0版本至1.9.1之前版本存在安全漏洞，该漏洞源于SamlSerializer在使用非X.509签名令牌验证SAML令牌时跳过了最终的SignatureValue验证，可能导致攻击者引用非X.509 SecurityToken密钥标识符并绕过断言签名验证。

CVSS 7.4 · High EPSS 0.20% · P9

Possible ATT&CK Techniques 1 AI

T1558.004 · AS-REP Roasting

Affected Version Matrix 2

VendorProduct Version RangeStatus
CoreWCF CoreWCF >= 1.9.0, < 1.9.1 affected
< 1.8.1 affected
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I. Basic Information for CVE-2026-54774

Vulnerability Information
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Vulnerability Title
CoreWCF: SamlSerializer skips SignatureValue verification when SAML signing token is not an X.509 certificate
Source: CVE Program / CVE List V5
Vulnerability Description
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.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N
Source: CVE Program / CVE List V5
Vulnerability Type
对数据真实性的验证不充分
Source: CVE Program / CVE List V5
Vulnerability Title
CoreWCF 输入验证错误漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
CoreWCF是CoreWCF团队开源的一个开源项目,旨在为 .NET Core 和 .NET 5+ 提供 WCF(Windows Communication Foundation)的替代实现。 CoreWCF 1.8.1之前版本和1.9.0版本至1.9.1之前版本存在安全漏洞，该漏洞源于SamlSerializer在使用非X.509签名令牌验证SAML令牌时跳过了最终的SignatureValue验证，可能导致攻击者引用非X.509 SecurityToken密钥标识符并绕过断言签名验证。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
CoreWCF CoreWCF >= 1.9.0, < 1.9.1 -

II. Public POCs for CVE-2026-54774

# POC Description Source Link Shenlong Link
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Qwen3.6-35B-A3B · 13514 chars
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III. Intelligence Information for CVE-2026-54774

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Patches & Fixes for CVE-2026-54774 (3)

Vendor Advisories for CVE-2026-54774 (1)

Vendor Pages for CVE-2026-54774 (1)

Other References for CVE-2026-54774 (1)

Same Patch Batch · CoreWCF · 2026-07-08 · 13 CVEs total

CVE-2026-54782 10.0 CRITICAL CoreWCF: Authentication bypass in CoreWCF SAML 1.1 / 2.0 token signature validation
CVE-2026-54772 7.5 HIGH CoreWCF: Pre-authentication infinite-loop CPU exhaustion in CoreWCF net.tcp / net.pipe / n
CVE-2026-54783 7.4 HIGH CoreWCF: XML Signature Wrapping in WS-Security endorsing/supporting signature verification
CVE-2026-54781 7.4 HIGH CoreWCF: SAML SubjectConfirmation methods and holder-of-key proof keys are not enforced
CVE-2026-54784 7.4 HIGH CoreWCF: SPNEGO SecurityContextToken proof key wrapped without confidentiality
CVE-2026-54775 6.5 MEDIUM CoreWCF: Kafka consume pump halts permanently on a Kafka tombstone (null-value record), ca
CVE-2026-54777 6.5 MEDIUM CoreWCF NetNamedPipe transport accepts attach to a pre-existing named pipe instance
CVE-2026-54778 6.2 MEDIUM CoreWCF: UnixDomainSocket Non-Reentrant POSIX Identity Resolution
CVE-2026-54779 5.9 MEDIUM CoreWCF: SAML token replay protection is inoperative
CVE-2026-54773 5.9 MEDIUM CoreWCF: WS-Security signature substitution via document-wide Signature lookup
CVE-2026-54776 4.4 MEDIUM CoreWCF: Unix Domain Socket PosixIdentity transport accepts connections that skip the secu
CVE-2026-54780 3.7 LOW CoreWCF: WS-Security Reference DigestMethod Algorithm-Suite Bypass

IV. Related Vulnerabilities

Same product: CoreWCF
Same vendor: CoreWCF
Same weakness: CWE-345

V. Comments for CVE-2026-54774

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