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Vulnerability record · CVE-2025-66415 · published 1 December 2025

CVE-2025-66415: Fastify reply-from vulnerability

Fastify · Reply From

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.

6.9 CVSS 4.0 Medium EPSS 0.18% · top 93.4% CWE-441 · CWE-441
6.9CVSS 4.0 base score
0.18%EPSS exploitation probability, 30 days
NoNot in CISA KEV
1Affected product versions listed by NVD
2References
17 Jun 2026Last modified by NVD

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.

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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:

Affected products

1 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://github.com/fastify/fastify-reply-from/commit/4d9795cd5b57a36756d37b7f036eae369f69fa66 Patch
https://github.com/fastify/fastify-reply-from/security/advisories/GHSA-2q7r-29rg-6m5h Vendor Advisory

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Related vulnerabilities

Same products first, then exploited flaws of the same weakness class.

9.0CVE-2026-33805Fastify\/http-proxy http request smuggling vulnerability@fastify/reply-from v12.6.1 and earlier and @fastify/http-proxy v11.4.3 and earlier process the client's Connection header after the proxy has added …EPSS 0.56%7.5CVE-2023-51701Fastify reply-from http request smuggling vulnerabilityfastify-reply-from is a Fastify plugin to forward the current HTTP request to another server. A reverse proxy server built with `@fastify/reply-from`…EPSS 0.48%10.0CVE-2026-83548SonicWall SMA1000 pre-auth SSRF via alternate access pathThe SMA1000 Appliance Work Place interface exposes an unintended alternate access path that allows server-side request forgery before authentication.…KEVEPSS 8.8%analysed

Source: NIST National Vulnerability Database (record CVE-2025-66415), CISA KEV, FIRST EPSS (scores of 2026-09-28). This page is refreshed as NVD updates the record.