What is CVE-2026-54782?

CVE-2026-54782 is a critical-severity vulnerability in Corewcf, classified under Authentication Bypass by Spoofing. CVSS score: 10.0/10. Published 2026-07-08.

How severe is CVE-2026-54782?

Critical severity. CVSS v3 base score is 10.0 out of 10.

Vulnerability in Corewcf

CVE-2026-54782

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, CoreWCF SAML 1.1 and SAML 2.0 token validation does not correctly resolve the issuer signing key or require signed tokens when IdentityConfiguration is used with federated bindings, allowing an unauthenticated remote attacker to impersonate any principal the trusted STS could issue. This issue is fixed in versions 1.8.1 and 1.9.1.

Published 2026-07-08 · last modified 2026-07-10.

CVSS v3 metric

CVSS v3 base score 10.0 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:N.

EPSS exploit prediction

EPSS: 0.004 (33.7th percentile), scored 2026-10-09.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 34th percentile — 33.7% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.004 · newest: 0.004 · change: 0.000

Affected products

Corewcf — versions >= 1.9.0, < 1.9.1, < 1.8.1

Weakness classification (CWE)

References

Frequently asked questions

What is CVE-2026-54782?: CVE-2026-54782 is a critical-severity vulnerability in Corewcf, classified under Authentication Bypass by Spoofing. CVSS score: 10.0/10. Published 2026-07-08.
How severe is CVE-2026-54782?: Critical severity. CVSS v3 base score is 10.0 out of 10.