CVE-2024-21498: Server-Side Request Forgery in github.com/greenpau/caddy-security

The vulnerability stems from improper handling of the X-Forwarded-Host header in two key areas: QR code generation and redirect logic. The GitHub issue (#269) explicitly references code in respond_qrcode.go (line 38) and redirect.go (lines 69-101) where these headers are processed. The Trail of Bits blog confirms these functions use untrusted headers to construct security-sensitive URLs without validation, creating SSRF vectors. Both functions directly process attacker-controlled headers to determine system behavior, meeting the criteria for SSRF vulnerability root causes.