Glossary

ReDoS

Regular expression denial of service

A pattern with nested or overlapping quantifiers takes exponential or polynomial time on crafted input in a backtracking regex engine. Use a linear-time engine such as RE2 or Rust’s regex, bound the input length, or rewrite the pattern.

Also called: catastrophic backtracking
Fix it in your stack: Regular-expression denial of service (ReDoS) fix cards (4 stacks) · CWE-1333 page
Defined in: MITRE CWE-1333
Identifiers: CWE-1333: Inefficient regular expression complexity

Covered in

Guide

Validate input safely and prevent regex denial of service

Find and fix exponential and quadratic regex backtracking with measured examples, choose linear-time engines or timeouts, and build allowlist validation that decodes once and rejects type confusion and parameter pollution.