undici vulnerable to cross-origin request routing via SOCKS5 proxy pool reuse
Published 19 Jun 2026 · Updated 10 Sept 2026
Affected packages
- Affected
- >=7.23.0 <7.28.0
- Fixed in
- 7.28.0
npm install undici@7.28.0- Affected
- >=8.0.0 <8.2.0
- Fixed in
- 8.2.0
npm install undici@8.2.0Details
Impact
When using Socks5ProxyAgent, undici reuses a single connection pool across different origins without verifying that the pool's origin matches the requested origin. All requests are dispatched through the pool connected to the first origin, regardless of the intended destination.
This causes cross-origin request routing: credentials and request data intended for origin B are sent to origin A, responses from the wrong origin are trusted, and HTTPS requests may be silently downgraded to HTTP.
Impacted users are applications that use Socks5ProxyAgent (directly or via setGlobalDispatcher) and make requests to more than one origin.
This was introduced in undici 7.23.0 via #4385 and affects all versions through 8.1.0.
Patches
Upgrade to undici v7.28.0 or v8.2.0
Workarounds
Use a separate Socks5ProxyAgent instance per origin, or avoid using Socks5ProxyAgent with multiple origins.
Is GHSA-hm92-r4w5-c3mj in any of your client repos?
Checking one package by hand is fine. Checking it across forty client projects is not. NPMscan reads the lockfiles in every GitHub repo you pick, finds each project with an affected undici, and gives you the command that fixes it.
References
Advisory data from OSV.dev (opens OSV.dev in a new tab), refreshed daily.