Double Encoding
Noun · Security & Infosec
Definitions
The practice of encoding input twice, often to bypass filters that decode or inspect data only once before passing it deeper into a system. Attackers use double encoding to sneak dangerous characters or paths past naive validation layers.
In plain English: Encoding data twice so filters miss what it really contains.
Example: "The path traversal worked because the gateway blocked `%2e%2e` but failed on a double encoding variant."