CVE-2026-5545 is a vulnerability involving the incorrect reuse of HTTP Negotiate authentication connections, which could allow an attacker to hijack or impersonate authenticated sessions. This type of flaw can lead to unauthorised access to resources by exploiting the way authentication tokens are shared across connections. It is particularly concerning in environments where multiple users or services share HTTP connections.

Security Architect’s Take: Review any services or middleware that use HTTP Negotiate (Kerberos/NTLM) authentication and ensure connection pooling is configured to enforce strict session isolation. Apply the relevant Microsoft patches promptly and consider monitoring for anomalous authentication patterns that could indicate session hijacking.

Original advisory: CVE-2026-5545 wrong reuse of HTTP Negotiate connection