Is CVE-2026-120213 exploited in the wild?

No. Junglewise Threat Intelligence has no report of CVE-2026-120213 being exploited in the wild.

How severe is CVE-2026-120213?

Critical severity, with a CVSS score of 9.1, published 2 November 2026.

Which products and versions are affected?

OpenJS Foundation @Fastify/Http-Proxy 9.0.0 through 11.6.5.

Is there a fix for CVE-2026-120213?

Yes: fixed in @fastify/http-proxy 11.6.6. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

How is CVE-2026-120213 attacked?

It is attacked over the network.

Am I affected by CVE-2026-120213?

Check whether you run OpenJS Foundation @Fastify/Http-Proxy at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

CVE-2026-120213: @fastify/http-proxy prefix escape via decoded route parameters

CVE-2026-120213 · Severity: critical · CVSS 9.1 · Published 2026-11-02

@fastify/http-proxy is a Fastify plugin that proxies HTTP requests to an upstream server under a configured prefix. Versions 9.0.0 through 11.6.5 fail to properly re-encode URL-decoded route parameters when rewriting upstream paths, allowing an attacker to inject path segments and bypasses the intended access restrictions. This can lead to unauthorized access to upstream resources outside the intended scope, server-side request forgery, or authorization bypass depending on the upstream configuration.

Vendors: OpenJS Foundation.

Quick answers

Is CVE-2026-120213 exploited in the wild?: No. Junglewise Threat Intelligence has no report of CVE-2026-120213 being exploited in the wild.
How severe is CVE-2026-120213?: Critical severity, with a CVSS score of 9.1, published 2 November 2026.
Which products and versions are affected?: OpenJS Foundation @Fastify/Http-Proxy 9.0.0 through 11.6.5.
Is there a fix for CVE-2026-120213?: Yes: fixed in @fastify/http-proxy 11.6.6. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is CVE-2026-120213 attacked?: It is attacked over the network.
Am I affected by CVE-2026-120213?: Check whether you run OpenJS Foundation @Fastify/Http-Proxy at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

How to fix

Fixed in: @fastify/http-proxy 11.6.6

Technical details

The vulnerability occurs in versions 9.0.0 through 11.6.5 where URL-decoded route parameters are substituted into rewritePrefix without re-encoding special characters. An attacker can craft a request with percent-encoded path separators (/) combined with fragment (#) or query (?) delimiters that, when decoded, inject extra path segments and strip the mandatory suffix enforcement, bypassing path restrictions without dot-dot traversal. This is a path traversal vulnerability (CWE-22) requiring only network access and no authentication.

Affected products

OpenJS Foundation @fastify/http-proxy 9.0.0 through 11.6.5

Timeline

2026-11-02: disclosed

References

This page as Markdown. Free to reuse under CC BY 4.0 with a link back.