Callback-url-file-3a-2f-2f-2fproc-2fself-2fenviron -

Its presence indicates someone is probing your application for a path traversal or SSRF vulnerability.

In secure systems, this string should never appear in any legitimate traffic. Treat it as what it is: a direct attack on your application’s confidentiality. callback-url-file-3A-2F-2F-2Fproc-2Fself-2Fenviron

$callback = $_GET['callback_url']; $response = file_get_contents($callback); An attacker changes it to: Its presence indicates someone is probing your application

| Encoded | Decoded | Meaning | |---------|---------|---------| | file-3A-2F-2F-2F | file:/// | URL scheme for local file access | | proc-2Fself-2Fenviron | proc/self/environ | Path to current process environment | $response = file_get_contents($callback)

Thus, the full decoded path is: