JIT Spray.

An exploit technique that abuses just-in-time compilers to plant attacker-chosen executable bytes inside legitimately generated, executable memory pages. It belongs to the Application Security category of cybersecurity.

An exploit technique that abuses just-in-time compilers to plant attacker-chosen executable bytes inside legitimately generated, executable memory pages.

JIT spray is a memory-corruption exploit technique used against runtimes with just-in-time compilers — JavaScript engines such as V8, SpiderMonkey, and JSC, the .NET CLR, the JVM, ActionScript, or eBPF. The attacker crafts a high-level program whose JIT-compiled output, when viewed as raw bytes, decodes into desired native instructions, allowing payload smuggling into RWX pages produced by the JIT. Combined with a memory-corruption bug that hijacks control flow, the attacker can pivot into the sprayed gadgets, bypassing data-execution protections because the memory is legitimately marked executable. Modern mitigations include constant blinding, randomized code regions, W^X JIT writeable/executable separation, ASLR, and CFI.

Defences for JIT Spray typically combine technical controls and operational practices, as detailed in the full definition above.

Common alternative names include: Just-in-time spray.