# CVE-2026-4926

## Summary

- **CVE ID:** CVE-2026-4926
- **Severity:** HIGH
- **CVSS Score:** 7.5 (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H)
- **CWE:** CWE-400, CWE-1333
- **Published:** Mar 26, 2026
- **Last Modified:** Sep 17, 2026

## 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.

## Affected Products

- path-to-regexp — path-to-regexp (8.0.0)
- path-to-regexp — path-to-regexp (8.4.0)

## References

- [CNA](https://cna.openjsf.org/security-advisories.html)
- [redhat-SADP](https://access.redhat.com/security/cve/CVE-2026-4926)
- [redhat-SADP](https://bugzilla.redhat.com/show_bug.cgi?id=2451867)
- [redhat-SADP](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-4926.json)
- [redhat-SADP](https://access.redhat.com/errata/RHSA-2026:24761)
- [redhat-SADP](https://access.redhat.com/errata/RHSA-2026:24762)
- [redhat-SADP](https://access.redhat.com/errata/RHSA-2026:17789)
- [redhat-SADP](https://access.redhat.com/errata/RHSA-2026:19409)
- [redhat-SADP](https://access.redhat.com/errata/RHSA-2026:19410)
- [redhat-SADP](https://access.redhat.com/errata/RHSA-2026:24866)
- [redhat-SADP](https://access.redhat.com/errata/RHSA-2026:13545)
- [redhat-SADP](https://access.redhat.com/errata/RHSA-2026:9742)
- [redhat-SADP](https://access.redhat.com/errata/RHSA-2026:13826)
- [redhat-SADP](https://access.redhat.com/errata/RHSA-2026:10175)
- [redhat-SADP](https://access.redhat.com/errata/RHSA-2026:9385)
- [redhat-SADP](https://access.redhat.com/errata/RHSA-2026:10172)
- [redhat-SADP](https://access.redhat.com/errata/RHSA-2026:10153)
- [redhat-SADP](https://access.redhat.com/errata/RHSA-2026:36651)
- [redhat-SADP](https://access.redhat.com/errata/RHSA-2026:40118)
- [redhat-SADP](https://access.redhat.com/errata/RHSA-2026:40945)
- [redhat-SADP](https://access.redhat.com/errata/RHSA-2026:50300)
- [redhat-SADP](https://access.redhat.com/errata/RHSA-2026:65126)

## Exploitation Prediction (EPSS)

- **EPSS Score:** 0.79%
- **EPSS Percentile:** 54.5

---
_Exported from OnDuty AI Vulnerability Intelligence on 2026-09-17._