CVE-2026-6253 is a vulnerability in a Microsoft Azure-related component where proxy credentials can be inadvertently leaked when an HTTP redirect causes a request to be forwarded to a different proxy. An attacker who can influence redirect behaviour could potentially intercept or capture credentials used for proxy authentication, gaining unauthorised access to network resources or sensitive systems behind the proxy.

Security Architect’s Take: Audit any Azure workloads or clients that authenticate to proxy servers — particularly those that follow HTTP redirects automatically — and apply Microsoft’s patch or workaround immediately. Consider enforcing proxy credential stripping on redirects at the network layer and reviewing proxy authentication logs for anomalous access patterns.

Original advisory: CVE-2026-6253 proxy credentials leak over redirect-to proxy