SB2026110964 - Multiple vulnerabilities in path-to-regexp

Description

This security bulletin contains information about 2 vulnerabilities.

1) Inefficient regular expression complexity (CVE-ID: CVE-2026-4923)

CWE-ID: CWE-1333 - Inefficient Regular Expression Complexity

CVSSv4: 8.2 [CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N]

The vulnerability allows an unauthenticated remote attacker to cause denial of service in applications using path-to-regexp for path matching.

The vulnerability exists due to excessive regular expression backtracking in path-to-regexp when a configured path contains multiple wildcards and at least one parameter, with the second wildcard positioned before the end of the path. An unauthenticated remote attacker can submit a crafted path to trigger expensive matching and exhaust application processing resources.

2) Resource exhaustion (CVE-ID: CVE-2026-4926)

CWE-ID: CWE-400 - Resource exhaustion

CVSSv4: 8.7 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N]

The vulnerability allows an unauthenticated remote attacker to cause denial of service in applications that accept user-controlled route patterns.

The vulnerability exists due to exponential growth in regular expressions generated by path-to-regexp when route patterns contain multiple sequential optional groups using curly brace syntax. An unauthenticated remote attacker can submit a route pattern containing many such groups to exhaust resources during regular expression generation.

Remediation

Install update from vendor's website.

References

• https://github.com/pillarjs/path-to-regexp/security/advisories/GHSA-27v5-c462-wpq7
• https://github.com/pillarjs/path-to-regexp/security/advisories/GHSA-j3q9-mxjg-w52f