CVE-2026-4867Network attack vector

Service interruption via overlapping route capture groups

Published Mar 26, 2026 · Updated Mar 26, 2026

Regular expression denial of service in PillarJS path-to-regexp before 0.1.13 allows remote attackers to interrupt services via crafted paths. The route compiler generates overlapping default capture groups when a segment contains at least three parameters separated by nonperiod characters because its lookahead fails to exclude single-character separators. Exposure requires a consuming application to use such a route without custom parameter expressions and to match attacker-controlled paths, causing catastrophic backtracking and CPU exhaustion.

CVSS severity7.5
High
EPSS probability0.50%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

Regular expression denial of service in PillarJS path-to-regexp before 0.1.13 allows remote attackers to interrupt services via crafted paths. The route compiler generates overlapping default capture groups when a segment contains at least three parameters separated by nonperiod characters because its lookahead fails to exclude single-character separators. Exposure requires a consuming application to use such a route without custom parameter expressions and to match attacker-controlled paths, causing catastrophic backtracking and CPU exhaustion.

The record

CVE
CVE-2026-4867
Published
Mar 26, 2026
Updated
Mar 26, 2026
Vendor
PillarJS
Product
path-to-regexp
Classifications
CWE-1333, CAPEC-492, T1499.003
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Mar 26, 2026CVE publishedPublication date reported by the CVE source.
  2. Mar 26, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=0 <0.1.13

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

PillarJS · path-to-regexpversion=0 <0.1.13

Published CVSS scores

7.5GitHubCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-1333Inefficient Regular Expression Complexity
CAPEC-492Regular Expression Exponential Blowup
T1499.003Application Exhaustion Flood

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo