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Vulnerability record · CVE-2026-54774 · published 8 July 2026

CVE-2026-54774: Insufficient verification of data authenticity vulnerability

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.

7.4 CVSS 3.1 High EPSS 0.20% · top 90.8% CWE-345 · Insufficient verification of data authenticityCWE-347 · Improper verification of cryptographic signature Deferred
7.4CVSS 3.1 base score
0.20%EPSS exploitation probability, 30 days
NoNot in CISA KEV
0Affected product versions listed by NVD
6References
10 Jul 2026Last modified by NVD

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.

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N

References

LinkTags
https://github.com/CoreWCF/CoreWCF/commit/65d09022749854ba943e376aefb958dec05b00d8
https://github.com/CoreWCF/CoreWCF/commit/b914495ce63c44924664643b60a262e7595081a4
https://github.com/CoreWCF/CoreWCF/commit/e7454132876ecc7e2cf80e541a44376eeb54979b
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/security/advisories/GHSA-rpj7-hr7h-w6p9

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Same products first, then exploited flaws of the same weakness class.

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Source: NIST National Vulnerability Database (record CVE-2026-54774), CISA KEV, FIRST EPSS (scores of 2026-09-26). This page is refreshed as NVD updates the record.