CVE-2026-54289
MediumCVSS 4.8Exploitation Probability (EPSS)
Low risk2th percentile — higher than 2% of all known CVEs
Summary
Hono is a web application framework that prior to version 4.12.25 on AWS Lambda@Edge had an issue with repeated request headers. The adapter wrote header values using Headers.set, causing earlier values to be overwritten, and only the last one reached the application.
Risk Assessment
For applications that base access control on the X-Forwarded-For chain, this vulnerability can weaken or alter access decisions. For auditing, hop history is lost.
Recommendation
It is recommended to upgrade to version 4.12.25 to eliminate this vulnerability and restore full functionality of request headers.
Original NVD description (English source)
Hono is a Web application framework that provides support for any JavaScript runtime. Prior to 4.12.25, on AWS Lambda@Edge, CloudFront delivers a request header that appears more than once as several separate entries. The adapter writes each value with Headers.set instead of Headers.append, so every value overwrites the previous one and only the last reaches the application. Repeated request headers such as X-Forwarded-For, Forwarded, and Via are silently truncated to a single value. Request middleware sees only the last value of a repeated header instead of the full chain. For applications that base access control on the X-Forwarded-For chain, this can weaken or alter that decision; for auditing, hop history is lost. This vulnerability is fixed in 4.12.25.