CVE-2026-59897: hono — Fix

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.

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CVSS v3.1 Score

4.8

MEDIUM

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N

EPSS — Exploit Prediction

0.0013

Probability of exploitation

0.03%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-348 CWE-348

Affected Products

Vendor	Product	Versions
hono	hono	4.3.3 — 4.12.27

References

Advisories & Patches

https://github.com/honojs/hono/commit/aa921770d09bc35970362d5a2630a878f6d982fd https://github.com/honojs/hono/security/advisories/GHSA-xgm2-5f3f-mvvc

Other References

https://github.com/honojs/hono/releases/tag/v4.12.27

Frequently Asked Questions

What is CVE-2026-59897? +

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. It has a CVSS v3.1 base score of 4.8 (MEDIUM).

How severe is CVE-2026-59897? +

CVE-2026-59897 has a CVSS v3.1 score of 4.8 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance. The EPSS score is 0.0013, placing it in the 0th percentile for exploitation probability.

What products are affected by CVE-2026-59897? +

CVE-2026-59897 affects products from hono, specifically: hono. Check the affected products table above for specific version ranges.

How do I check if I'm vulnerable to CVE-2026-59897? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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