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.
History

Mon, 02 Nov 2026 22:30:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'poc', 'Technical Impact': 'partial'}, 'version': '2.0.3'}


Sat, 31 Oct 2026 00:30:00 +0000

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References
Metrics threat_severity

None

threat_severity

Important


Wed, 28 Oct 2026 22:15:00 +0000

Type Values Removed Values Added
First Time appeared Le0pard
Le0pard re2js
Vendors & Products Le0pard
Le0pard re2js

Wed, 28 Oct 2026 17:30:00 +0000

Type Values Removed Values Added
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.
Title RE2JS: Quadratic-time denial of service in re2js lookbehind matching
Weaknesses CWE-1333
CWE-407
References
Metrics cvssV3_1

{'score': 7.5, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H'}


cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published: 2026-10-28T17:14:15.988Z

Updated: 2026-11-02T20:21:58.052Z

Reserved: 2026-10-26T21:53:35.168Z

Link: CVE-2026-116795

cve-icon Vulnrichment

Updated: 2026-11-02T20:21:53.348Z

cve-icon NVD

Status : Awaiting Analysis

Published: 2026-10-28T18:17:14.303

Modified: 2026-11-02T21:17:25.320

Link: CVE-2026-116795

cve-icon Redhat

Severity : Important

Publid Date: 2026-10-28T17:14:15Z

Links: CVE-2026-116795 - Bugzilla