Chapter 4 – Test Analysis & Design
Fuzz Testing – ISTQB Definition
Last Updated: July 12, 2026 · SoftwareTestPilot QA Team
Official ISTQB Definition
A software testing technique used to discover security vulnerabilities by inputting massive amounts of random data to the system in an attempt to make it crash.
In simple words
Bombard the system with malformed, random or unexpected inputs and see what breaks.
Exam tip
Fuzzing is the fastest way to find crash bugs in parsers, APIs and file handlers — used heavily in security testing.
Related terms
- Syntax TestingGenerate tests from the grammar of the inputs (e.g. a BNF) — one test per production rule, plus invalid mutations.
- Security TestingTrying to break in, leak data, or escalate privileges — before an attacker does.
- Negative TestingDeliberately feeding the system bad or unexpected inputs to prove it fails gracefully instead of crashing.
Practice this term in the ISTQB Mock Test
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