For environments where curl is used programmatically via libcurl , explicitly disable the FILE protocol:
curl file:///etc/passwd
The keyword in question uses percent-encoding, also known as . This encoding mechanism converts special characters into a %XX hexadecimal format, allowing them to be safely transmitted in URLs. curl-url-file-3A-2F-2F-2F
SSRF occurs when an attacker forces a web application to make an internal backend request. If the web application uses curl or libcurl under the hood to fetch a user-provided URL (e.g., "Import profile picture from URL"), an attacker might provide file:///etc/passwd instead of an https:// link. Vulnerable Input Intended Protocol Actual Exploit Action For environments where curl is used programmatically via
Developers and system administrators encounter this specific syntax framework in a few distinct scenarios. "Import profile picture from URL")
curl "file://attacker.com/share/secret.txt"