# CVE-2026-39409

## Summary

- **CVE ID:** CVE-2026-39409
- **Severity:** MEDIUM
- **CVSS Score:** 6.3 (CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N)
- **CWE:** CWE-180
- **Published:** Apr 8, 2026
- **Last Modified:** Apr 8, 2026

## Description

Hono is a Web application framework that provides support for any JavaScript runtime. Prior to 4.12.12, ipRestriction() does not canonicalize IPv4-mapped IPv6 client addresses (e.g. ::ffff:127.0.0.1) before applying IPv4 allow or deny rules. In environments such as Node.js dual-stack, this can cause IPv4 rules to fail to match, leading to unintended authorization behavior. This vulnerability is fixed in 4.12.12.

## Affected Products

- honojs — hono (< 4.12.12)

## References

- [CNA](https://github.com/honojs/hono/security/advisories/GHSA-xpcf-pg52-r92g)
- [CNA](https://github.com/honojs/hono/commit/48fa2233bc092f650119f42df043050737cabf39)
- [CNA](https://github.com/honojs/hono/releases/tag/v4.12.12)

## Exploitation Prediction (EPSS)

- **EPSS Score:** 0.34%
- **EPSS Percentile:** 27.2

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_Exported from OnDuty AI Vulnerability Intelligence on 2026-09-10._