CVE-2026-54289 Hono: Lambda@Edge adapter keeps only the last value of a repeated request header, dropping the rest
The Hono Lambda@Edge adapter truncates repeated request headers, potentially hiding IP chains and weakening access control decisions based on X-Forwarded-For.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-54289?
CVE-2026-54289 is a medium-severity vulnerability in honojs hono, published on 22 Jun 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
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.
Weakness: CWE-348
Which versions are affected by CVE-2026-54289?
2 open source packages ship an affected version, including hono.
| Package | Affected | Fixed in |
|---|---|---|
hono npm | All versions | 4.12.25 |
hono npm | All versions | 4.12.25 |
How do I fix CVE-2026-54289?
Upgrade hono to 4.12.25 or later.
Is CVE-2026-54289 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-54289 exists.
Sources
Also known as ECHO-d0c1-0187-7821, GHSA-wgpf-jwqj-8h8p, MINI-27rm-jq4x-vpqj, MINI-7627-xppq-r9r5, MINI-96hx-6pp7-fh57, MINI-c4c8-hjwq-4ccf and 9 more.