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.
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Exploitation outlook
- Low exploitation risk0.12% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 3% of all EPSS-scored CVEs.
Advisory coverage (1)
External references
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[](https://www.csirts.com/cve/CVE-2026-59897)