CVE-2026-116795: RE2JS: Quadratic-time denial of service in re2js lookbehind matching

October 28, 2026

Using the opt-in LOOKBEHINDS flag together with any repeated-matching API (matcher().find() in a loop, matchAll(), split(), matcher().replaceAll()) causes quadratic-time (Θ(n²)) matching, contradicting the library’s own “linear time matching” guarantee. A single call with a 16,000-character input takes 36.7–38.7 seconds of CPU.

References

github.com/advisories/GHSA-gg6h-894w-4m9c
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
nvd.nist.gov/vuln/detail/CVE-2026-116795

Code Behaviors & Features

Detect and mitigate CVE-2026-116795 with GitLab Dependency Scanning

Secure your software supply chain by verifying that all open source dependencies used in your projects contain no disclosed vulnerabilities. Dependency Scanning using SBOM also detects vulnerabilities from proprietary advisories that this site does not include. Learn more about Dependency Scanning using SBOM →