CVE-2026-78428

High CVSS 8

Published 2026-09-17 · last changed 2026-09-18

The fix

We hold no Microsoft remediation data for CVE-2026-78428, which normally means it is not a Windows CVE. For non-Microsoft software the fix is the vendor's own updated release, and the affected versions are listed below.

What it is

For users authenticated through SAML or OpenID Connect (OIDC), this vulnerability can result in one user receiving another user's authenticated session when multiple SSO login attempts occur concurrently

Sources

NVD record for CVE-2026-78428

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