URL Credential Confusion Attack via @ Symbol Injection in HTTP Query Parameter

Ibrahim Saud@tektrix

•updated Jun 30, 2026•0•0•2

Detects URL credential confusion attempts where an attacker injects an @ symbol into URL-based query parameters. By including an '@' character, the attacker forces a mismatch between how a hostname validator parses the URL (seeing a legitimate hostname like github.com as the userinfo component) and how the backend fetcher resolves the URL (ignoring the userinfo and resolving the host following the @ symbol), potentially enabling Server-Side Request Forgery (SSRF) or local file read bypasses.