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

Status: published. Published: 2026-10-28. Updated: 2026-11-02.

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.

## Remediation

- fix: re2js (npm): OSV reports a fixed version 2.8.7. Check the advisory for supported release branches. (source: OSV GHSA-gg6h-894w-4m9c) — https://github.com/advisories/GHSA-gg6h-894w-4m9c

## Affected products and versions

- le0pard / re2js: >= 2.2.0, < 2.8.7 (affected). Source: CNA: GitHub_M
-  / re2js (re2js): ≥ 2.2.0; < 2.8.7 (affected, semver); OSV events: introduced 2.2.0; fixed 2.8.7. Source: OSV GHSA-gg6h-894w-4m9c

## Severity and prioritization

- CVSS 3.1: 7.5 (high); CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H; source: CNA: GitHub_M

- CISA KEV: No listing in collected sources

- EPSS: 0.46% as of 2026-11-02; percentile 40.24%

- SSVC: exploitation poc; automatable yes; technical impact partial; source ADP: CISA-ADP

- Weaknesses: CWE-407, CWE-1333

## Exploit evidence

- exploit: https://github.com/le0pard/re2js/security/advisories/GHSA-gg6h-894w-4m9c (ADP: CISA-ADP)

## References

- https://github.com/le0pard/re2js/security/advisories/GHSA-gg6h-894w-4m9c (CNA: GitHub_M; x_refsource_CONFIRM)

- https://github.com/le0pard/re2js/pull/59 (CNA: GitHub_M; x_refsource_MISC)

- https://github.com/le0pard/re2js/commit/dfdd947785dfa113bdc97416375c246a39458395 (CNA: GitHub_M; x_refsource_MISC)

- https://github.com/le0pard/re2js/releases/tag/2.8.7 (CNA: GitHub_M; x_refsource_MISC)

- https://github.com/le0pard/re2js/security/advisories/GHSA-gg6h-894w-4m9c (ADP: CISA-ADP; exploit)

- https://github.com/advisories/GHSA-gg6h-894w-4m9c (OSV / GitHub Security Advisories; advisory)

- https://osv.dev/vulnerability/GHSA-gg6h-894w-4m9c (OSV / GitHub Security Advisories; osv)

## Provenance

- CNA: GitHub_M: https://www.cve.org/CVERecord?id=CVE-2026-116795; retrieved 2026-11-02; source updated 2026-11-02

- OSV / GitHub Security Advisories: https://osv.dev/vulnerability/GHSA-gg6h-894w-4m9c; retrieved 2026-11-02; source updated 2026-10-28

- FIRST EPSS: https://api.first.org/data/v1/epss?cve=CVE-2026-116795; retrieved 2026-11-02; source updated Not reported

Revision: d1bdc313112a5c05776d2a8c97204c3b0b79cd62cd6b82a7e48cf10b5a69f824

Canonical: https://y2.dev/cve/CVE-2026-116795

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