Vulnerability · Published Oct 8, 2026 · Assigned by openjs
CVE-2026-107318@fastify/reply-from vulnerable to improper certificate validation in built-in HTTPS transports
High 7.4
In plain English
A high-severity improper certificate validation in @fastify/reply-from from @fastify/reply-from. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.1% (higher than 4% of all known vulnerabilities).
Official description
@fastify/reply-from is a Fastify plugin that forwards requests to an upstream HTTP or HTTPS server. In versions prior to 12.7.0, all of the built-in HTTPS transports override the secure default and set rejectUnauthorized to false, so the proxy does not verify the TLS certificate of the upstream even when the application points it at an https upstream in the default configuration. An on-path network attacker can therefore impersonate the configured HTTPS upstream, read the credentials and request bodies the proxy forwards, and return forged responses that the application trusts. The issue is fixed in @fastify/reply-from 12.7.0, and users should upgrade to 12.7.0 or later. As a workaround, pass an explicit rejectUnauthorized true on the transport, supply an already configured undici instance, or use the undici global agent.
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| @fastify/reply-from | @fastify/reply-from | 0 – before 12.7.0 |
Weakness: CWE-295 · Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N