CVE-2026-116795

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

Published Oct 28, 2026 CVSS 3.1 · 7.5 High EPSS < 1% KEV · Not listed
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.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

Source ID Title
Github GHSA Github GHSA GHSA-gg6h-894w-4m9c RE2JS: Quadratic-time denial of service in re2js lookbehind matching
History
Type Values Removed Values Added
Metrics ssvc

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

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

Weaknesses

Sources

Status
PUBLISHED
Assigner
GitHub_M
Published
Updated
Nov 2, 2026, 8:21 PM
Reserved
Oct 26, 2026, 9:53 PM
Status
Awaiting Analysis
Published
Oct 28, 2026, 6:17 PM
Modified
Nov 2, 2026, 9:17 PM
Severity
Important
Public date
Oct 28, 2026, 5:14 PM