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CVE-2026-4926— path-to-regexp vulnerable to Denial of Service via sequential optional groups

Quick assessment

Affected
path-to-regexp path-to-regexp
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.

Path-to-RegExp是pillarjs开源的一个工具。用于将路径字符串转换为正则表达式。 Path-to-RegExp 8.4.0之前版本存在安全漏洞，该漏洞源于生成的正则表达式存在指数级增长问题，可能导致拒绝服务攻击。

CVSS 7.5 · High EPSS 0.89% · P58

Possible ATT&CK Techniques 1 AI

T1496 · Resource Hijacking

Affected Version Matrix 2

VendorProduct Version RangeStatus
path-to-regexp path-to-regexp 8.0.0< 8.4.0 affected
8.4.0 unaffected
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I. Basic Information for CVE-2026-4926

Vulnerability Information
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Vulnerability Title
path-to-regexp vulnerable to Denial of Service via sequential optional groups
Source: CVE Program / CVE List V5
Vulnerability Description
Impact: A bad regular expression is generated any time you have multiple sequential optional groups (curly brace syntax), such as `{a}{b}{c}:z`. The generated regex grows exponentially with the number of groups, causing denial of service. Patches: Fixed in version 8.4.0. Workarounds: Limit the number of sequential optional groups in route patterns. Avoid passing user-controlled input as route patterns.
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
未加控制的资源消耗(资源穷尽)
Source: CVE Program / CVE List V5
Vulnerability Title
Path-to-RegExp 安全漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Path-to-RegExp是pillarjs开源的一个工具。用于将路径字符串转换为正则表达式。 Path-to-RegExp 8.4.0之前版本存在安全漏洞，该漏洞源于生成的正则表达式存在指数级增长问题，可能导致拒绝服务攻击。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
path-to-regexp path-to-regexp 8.0.0 ~ 8.4.0 -

II. Public POCs for CVE-2026-4926

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III. Intelligence Information for CVE-2026-4926

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Same Patch Batch · path-to-regexp · 2026-03-26 · 3 CVEs total

CVE-2026-4867 7.5 HIGH path-to-regexp vulnerable to Regular Expression Denial of Service via multiple route param
CVE-2026-4923 5.9 MEDIUM path-to-regexp vulnerable to Regular Expression Denial of Service via multiple wildcards

IV. Related Vulnerabilities

Same product: path-to-regexp
Same vendor: path-to-regexp
Same weakness: CWE-400

V. Comments for CVE-2026-4926

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