CVE-2025-71381 Hono - Vary Header Injection in CORS Middleware
Attackers can inject Vary headers via CORS middleware, causing cache pollution and inconsistent CORS enforcement in shared cache environments.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2025-71381?
CVE-2025-71381 is a medium-severity vulnerability in Hono, published on 30 Jun 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
Hono before 4.10.3 contains a flaw in its CORS middleware: when the origin is not set to "*", the middleware copies the Vary header from the incoming request into the response. Because Vary is a response header that should be managed by the server, an attacker can supply arbitrary Vary values that are reflected into the response, potentially causing cache key pollution and inconsistent CORS enforcement in environments that rely on shared caches or proxies.
Weakness: CWE-113
Which versions are affected by CVE-2025-71381?
2 open source packages ship an affected version, including hono.
| Package | Affected | Fixed in |
|---|---|---|
hono npm | All versions | 4.10.3 |
hono npm | All versions | 4.10.3 |
How do I fix CVE-2025-71381?
Upgrade hono to 4.10.3 or later.
Is CVE-2025-71381 being exploited?
There is no known exploitation of CVE-2025-71381 in the wild and no public exploit code.
Sources
Also known as GHSA-q7jf-gf43-6x6p, MINI-vq54-q62q-3hqm.