CVE-2026-54774

CoreWCF: SamlSerializer skips SignatureValue verification when SAML signing token is not an X.509 certificate

HIGH
7.4
CVSS Score
Published: July 8, 2026 at 10:17 PM UTC
Updated: July 10, 2026 at 05:16 AM UTC
1 product affected across 1 vendorCoreWCF

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Severity
HIGH7.4
Exploit prediction
EPSS 0.2%
SSVC
No known exploit

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.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

v < 1.8.1v < 1.9.1
Affected range stops below 1.8.1, so it looks safe — our inference, not a vendor statement
Affected range stops below 1.9.1, so it looks safe — our inference, not a vendor statement

Remediation

No guide yet

No remediation guidance has been written for this CVE yet, and no fixed version or vendor advisory is recorded against it.

SSVC — Action Prioritization

SSVCNo known exploitNot automatableTotal impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

7.4HIGHGitHub_M
Attack Vector
NETWORK
Complexity
HIGH
Privileges
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
HIGH
Integrity
HIGH
Availability
NONE
Vector?

Quick Info

StatusDEFERRED
CWE
CWE-345CWE-347

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