On the Complexity of the Matching Problem of Regular Expressions with Backreferences
ReDoS is a well-known type of algorithmic complexity attack, where an adversary supplies maliciously crafted strings to a regular expression matching engine, aiming to exhaust computational resources of systems. Even quadratic-time behavior in matching engines has been exploited in successful attacks, as exemplified by major outages at Stack Overflow (2016) and Cloudflare (2019). These incidents motivate a fundamental question: Is it possible to construct matching engines that are provably efficient, running in (near-)linear time in the length of the input string? For classical regular expressions (REGEX), Thompson's construction yields a linear-time algorithm. However, practical engines ...
| Authors | Soh Kumabe, Yuya Uezato |
|---|---|
| Primary category | cs.DS |
| Published | 8 May 2026 |
| Last updated at source | 8 May 2026 |
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