Forward Authentication Vulnerability in nforwardauth by nosduco

CVE-2026-81509

What is CVE-2026-81509?

The nforwardauth service, which provides a centralized authentication method for multiple sites, has a vulnerability that arises from the lack of validation for the r query parameter on the /login endpoint in versions prior to 1.5.1. This flaw allows an unauthenticated attacker to craft a valid nforwardauth login URL that can redirect users to malicious websites post-authentication. Once victims authenticate, they are redirected to an attacker-controlled destination, which can lead to successful phishing and social engineering attacks that exploit the trust in the legitimate authentication site.

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