# CVE-2026-59897

## Summary

- **CVE ID:** CVE-2026-59897
- **Severity:** MEDIUM
- **CVSS Score:** 4.8 (CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N)
- **CWE:** CWE-348
- **Published:** Jul 8, 2026
- **Last Modified:** Jul 9, 2026

## Description

Hono is a Web application framework that provides support for any JavaScript runtime. From 4.3.3 before 4.12.27, the AWS API Gateway v1 adapter can drop a distinct repeated request header value because it de-duplicates values using a substring comparison instead of an exact match, so middleware or application logic that depends on the complete X-Forwarded-For chain, rate limiting, audit logging, or proxy-chain validation can receive incomplete data. This issue is fixed in version 4.12.27.

## Affected Products

- honojs — hono (>= 4.3.3, < 4.12.27)

## References

- [CNA](https://github.com/honojs/hono/security/advisories/GHSA-xgm2-5f3f-mvvc)
- [CNA](https://github.com/honojs/hono/commit/aa921770d09bc35970362d5a2630a878f6d982fd)
- [CNA](https://github.com/honojs/hono/releases/tag/v4.12.27)

## Exploitation Prediction (EPSS)

- **EPSS Score:** 0.18%
- **EPSS Percentile:** 7.6

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