The impact of regular expression denial of service (ReDoS) in practice: an empirical study at the ecosystem scale

Regular expressions (regexes) are a popular and powerful means of automatically manipulating text. Regexes are also an understudied denial of service vector (ReDoS). If a regex has super-linear worst-case complexity, an attacker may be able to trigger this complexity, exhausting the victim’s CPU resources and causing denial of service. Existing research has shown how to detect these superlinear regexes, and practitioners have identified super-linear regex anti-pattern heuristics that may lead to such complexity.