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

Quick assessment

Affected
le0pard re2js
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

RE2JS 是 RE2（一款提供线性时间匹配的正则表达式引擎）的 JavaScript 移植版本。在 2.2.0 至 2.8.7 版本中，若启用向后查找（LOOKBEHINDS）功能，并通过 、 、 或 等接口执行重复匹配，可能导致总体计算量呈二次方增长。具体而言， 方法会在每次请求新的起始位置时，从偏移量零开始重新执行向后查找扫描；而基于 的 API 则会请求捕获槽（capture slots），从而阻止了原本在无捕获匹配中可用的提前退出机制。因此，在存在密集匹配的情况下，输入内容会被反复重新扫描，使得攻击者可操

CVSS 7.5 · High

Possible ATT&CK Techniques 1 AI

T1499.002 · Service Exhaustion Flood

Affected Version Matrix 1

VendorProduct Version RangeStatus
le0pard re2js >= 2.2.0, < 2.8.7 affected
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I. Basic Information for CVE-2026-116795

Vulnerability Information
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Vulnerability Title
RE2JS: Quadratic-time denial of service in re2js lookbehind matching
Source: CVE Program / CVE List V5
Vulnerability 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.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Source: CVE Program / CVE List V5
Vulnerability Type
算法复杂性
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
le0pard re2js >= 2.2.0, < 2.8.7 -

II. Public POCs for CVE-2026-116795

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III. Intelligence Information for CVE-2026-116795

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Patches & Fixes for CVE-2026-116795 (1)

Vendor Advisories for CVE-2026-116795 (1)

Vendor Pages for CVE-2026-116795 (1)

IV. Related Vulnerabilities

Same weakness: CWE-407