Vulnerability · Published Dec 1, 2025 · Assigned by GitHub_M

CVE-2025-66415fastify-reply-from bypass of reply forwarding

Medium 6.9

In plain English

A medium-severity security flaw in fastify-reply-from from fastify. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.2% (higher than 9% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 4.0)6.9Medium

Exploit odds (30 days)0.2%top 91.1% of all CVEs

Exploited in the wildNo reportsCISA SSVC: none

Attack toolingNoneno public tooling known

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.

Affected packages & fixed versions

Ecosystem	Package	Fixed in	Advisory
npm	@fastify/reply-from	12.5.0	GHSA-2q7r-29rg-6m5h

Affected products (as reported)

Vendor	Product	Versions
fastify	fastify-reply-from	< 12.5.0

Weakness: CWE-441 · Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N

References

https://github.com/fastify/fastify-reply-from/security/advisories/GHSA-2q7r-29rg-6m5h x_refsource_CONFIRM
https://github.com/fastify/fastify-reply-from/commit/4d9795cd5b57a36756d37b7f036eae369f69fa66 x_refsource_MISC