Vulnerability · Published Jun 22, 2026 · Assigned by GitHub_M
CVE-2026-54289Hono: Lambda@Edge adapter keeps only the last value of a repeated request header, dropping the rest
Medium 4.8
In plain English
A medium-severity security flaw in hono from honojs. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.2% (higher than 7% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official description
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.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| npm | hono | 4.12.25 | GHSA-wgpf-jwqj-8h8p |
Affected products (as reported)
Weakness: CWE-348 · Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N
References
- https://github.com/honojs/hono/security/advisories/GHSA-wgpf-jwqj-8h8p x_refsource_CONFIRM