Path-to-regexp has a newer release, version 7.0.0, compared to the previous stable version 6.3.0. Both versions maintain the same description: "Express style path to RegExp utility," suggesting continued utility for developers needing to translate URL path patterns into regular expressions commonly used in routing. One notable difference lies in the dist section of the package metadata. Version 7.0.0 shows a significantly smaller unpackedSize of 59789 bytes and fileCount of 6, compared to version 6.3.0's 112042 bytes and 8 files. This suggests a potential optimization in the newer version, possibly leading to faster installation times and reduced disk space usage.
Both versions share a MIT license and point to the same GitHub repository, indicating consistent open-source availability and maintainership. The devDependencies are relatively similar, with both versions using tools like Typescript, size-limit, @types/node, @types/semver, @vitest/coverage-v8, and others. The presence of these tools highlights a commitment to code quality, type safety, and performance monitoring. The semver package itself is present in 6.3.0 but not in 7.0.0, meaning it was, possibly, removed from the dependencies since it was not longer used and it was merged with another utility.
The more recent releaseDate for version 7.0.0 (2024-06-20T23:10:50.676Z) confirms it contains the most up-to-date code and any potential bug fixes or improvements made since version 6.3.0 (2024-09-12T01:09:36.065Z). Developers should consider upgrading to version 7.0.0 to benefit from these optimizations and potential enhancements, keeping in mind to test the upgrade to make sure that there are no breaking changes for the specific use case and application.
All the vulnerabilities related to the version 7.0.0 of the package
path-to-regexp outputs backtracking regular expressions
A bad regular expression is generated any time you have two parameters within a single segment, separated by something that is not a period (.). For example, /:a-:b.
For users of 0.1, upgrade to 0.1.10. All other users should upgrade to 8.0.0.
These versions add backtrack protection when a custom regex pattern is not provided:
They do not protect against vulnerable user supplied capture groups. Protecting against explicit user patterns is out of scope for old versions and not considered a vulnerability.
Version 7.1.0 can enable strict: true and get an error when the regular expression might be bad.
Version 8.0.0 removes the features that can cause a ReDoS.
All versions can be patched by providing a custom regular expression for parameters after the first in a single segment. As long as the custom regular expression does not match the text before the parameter, you will be safe. For example, change /:a-:b to /:a-:b([^-/]+).
If paths cannot be rewritten and versions cannot be upgraded, another alternative is to limit the URL length. For example, halving the attack string improves performance by 4x faster.
Using /:a-:b will produce the regular expression /^\/([^\/]+?)-([^\/]+?)\/?$/. This can be exploited by a path such as /a${'-a'.repeat(8_000)}/a. OWASP has a good example of why this occurs, but the TL;DR is the /a at the end ensures this route would never match but due to naive backtracking it will still attempt every combination of the :a-:b on the repeated 8,000 -a.
Because JavaScript is single threaded and regex matching runs on the main thread, poor performance will block the event loop and can lead to a DoS. In local benchmarks, exploiting the unsafe regex will result in performance that is over 1000x worse than the safe regex. In a more realistic environment using Express v4 and 10 concurrent connections, this translated to average latency of ~600ms vs 1ms.
