RE2JS: Quadratic-time denial of service in re2js lookbehind matching

[ Why it matters ]Priority signals

• Public proof-of-concept exploit exists (CISA SSVC)

[ Description ]Official description

RE2JS is the JavaScript port of RE2, a regular expression engine that provides linear time matching. From 2.2.0 until 2.8.7, enabling LOOKBEHINDS and using repeated matching through matcher().find(), matchAll(), split(), or matcher().replaceAll() can cause quadratic total work. Machine.match restarts lookbehind scanning from offset zero for each requested start position, while Matcher-based APIs request capture slots that prevent the early exit used for captureless matching. Dense matches therefore repeatedly rescan the input, allowing attacker-influenced text to monopolize a single-threaded worker and deny service. This issue is fixed in version 2.8.7.

[ Fixes ]Fixes and patches

• re2js 2.8.7Fixed version · GitHub Advisories · npm package re2js: upgrade to 2.8.7 or later (affected >= 2.2.0, < 2.8.7)

[ Packages ]Affected open-source packages

• re2js npmAffected >= 2.2.0, < 2.8.7 · fixed in 2.8.7 · GHSA-gg6h-894w-4m9c

[ References ]References

• github.com/le0pard/re2js/commit/dfdd947785dfa113bdc97416375c246a39458395
• github.com/le0pard/re2js/pull/59
• github.com/le0pard/re2js/releases/tag/2.8.7
• github.com/le0pard/re2js/security/advisories/GHSA-gg6h-894w-4m9c