CVE-2025-66415 fastify-reply-from bypass of reply forwarding
Attackers can bypass route restrictions in fastify-reply-from to access unauthorized endpoints by crafting malicious URLs.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2025-66415?
CVE-2025-66415 is a medium-severity missing authorization vulnerability in fastify-reply-from, published on 1 Dec 2025. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
fastify-reply-from is a Fastify plugin to forward the current HTTP request to another server. Prior to 12.5.0, by crafting a malicious URL, an attacker could access routes that are not allowed, even though the reply.from is defined for specific routes in @fastify/reply-from. This vulnerability is fixed in 12.5.0.
Weakness: CWE-441
Which versions are affected by CVE-2025-66415?
2 open source packages ship an affected version, including @fastify/reply-from. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
@fastify/reply-from npm | All versions | 12.5.0 |
@fastify/reply-from npm | All versions | 12.5.0 |
Products include Fastify Reply-From.
How do I fix CVE-2025-66415?
Upgrade @fastify/reply-from to 12.5.0 or later.
Upgrade, and check permissions on every request on the server, not only in the interface. More about Missing authorization.
Is CVE-2025-66415 being exploited?
There is no known exploitation of CVE-2025-66415 in the wild and no public exploit code.
Other vulnerabilities in fastify-reply-from
Sources
Also known as GHSA-2q7r-29rg-6m5h.