GHSA-27v5-c462-wpq7 — medium GitHub Advisory (CVE-2026-4923) in npm/path-to-regexp

Description

Impact

When using multiple wildcards, combined with at least one parameter, a regular expression can be generated that is vulnerable to ReDoS. This backtracking vulnerability requires the second wildcard to be somewhere other than the end of the path.

Unsafe examples:

/*foo-*bar-:baz
/*a-:b-*c-:d
/x/*a-:b/*c/y

Safe examples:

/*foo-:bar
/*foo-:bar-*baz

Patches

Upgrade to version 8.4.0.

Workarounds

If developers are using multiple wildcard parameters, they can check the regex output with a tool such as https://makenowjust-labs.github.io/recheck/playground/ to confirm whether a path is vulnerable.

Basic information

Type: reviewed
Severity: medium
Advisory on GitHub: Open advisory ↗
Repository advisory: Open repository advisory ↗
Source code: Browse source ↗
Published (advisory): 2026-03-27 22:23:52 UTC
Updated: 2026-03-27 22:23:55 UTC
GitHub reviewed: 2026-03-27 22:23:52 UTC
NVD published: 2026-03-26

Score	Percentile
0.05%	16.47%

CVSS Scores

Base score	Version	Severity	Vector
5.9	3.1	—	`CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H` Click to expand Attack vector (AV:N) Could be attacked over the internet or any normal routed network—not just someone sitting at the machine. Attack complexity (AC:H) Even with access, the exploit needs extra luck, timing, or a fussy environment to actually work. Privileges required (PR:N) No account or special rights needed—anonymous or random user is enough. User interaction (UI:N) Nobody has to click “OK” or open a trap file; it can work without a victim helping. Scope (S:U) Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems. Confidentiality (C:N) Doesn’t really leak secrets in a meaningful way. Integrity (I:N) Data isn’t meaningfully altered or forged. Availability (A:H) Could take the service down hard or make it unusable for people who depend on it.

Identifiers

Type	Value
GHSA	GHSA-27v5-c462-wpq7 ↗
CVE	CVE-2026-4923 ↗

CWEs

CWE id	Name
CWE-1333	Inefficient Regular Expression Complexity

Credits

blakeembrey (remediation_developer)
UlisesGascon (remediation_reviewer)

Affected packages (1)

Vulnerable version ranges and first patched releases as published by GitHub.

Ecosystem	Package	Vulnerable range	First patched	Vulnerable functions
npm	path-to-regexp	>= 8.0.0, < 8.4.0	8.4.0	—

path-to-regexp vulnerable to Regular Expression Denial of Service via multiple wildcards