CVE-2026-4926
Description
A flaw was found in path-to-regexp. A remote attacker could exploit this vulnerability by providing specially crafted input that generates a regular expression with multiple sequential optional groups. This leads to an exponential growth in the generated regular expression, causing a Denial of Service (DoS) due to excessive resource consumption.
Statement
This is an Important flaw in path-to-regexp that can lead to a Denial of Service. The vulnerability occurs when specially crafted input containing multiple sequential optional groups is used to generate regular expressions, causing exponential resource consumption.
The Red Hat Advanced Cluster Security is not affected by this issue since it's shipping a path-to-regexp version which doesn't contain the vulnerable code.
Mitigation
To mitigate this vulnerability, limit the use of multiple sequential optional groups in route patterns within applications that use `path-to-regexp`. Additionally, avoid directly passing user-controlled input as route patterns to prevent the generation of maliciously crafted regular expressions.
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 7.5 | N/A | 7.5 |
| Attack Vector | Network | N/A | Network |
| Attack Complexity | Low | N/A | Low |
| Privileges Required | None | N/A | None |
| User Interaction | None | N/A | None |
| Scope | Unchanged | N/A | Unchanged |
| Confidentiality | None | N/A | None |
| Integrity Impact | None | N/A | None |
| Availability Impact | High | N/A | High |
Vector
Red Hat: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
cve.org: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Understanding the Weakness (CWE)
Availability
Technical Impact: DoS: Resource Consumption (CPU)
Attackers can create crafted inputs that intentionally cause the regular expression to use excessive backtracking in a way that causes the CPU consumption to spike.
Frequently Asked Questions
Not sure what something means? Check out our Security Glossary.
Want to get errata notifications? Sign up here.
