Overview
About vulnerability
ImpactWhen an application passes user-controlled input to the upgrade option of client.request(), an attacker can inject CRLF sequences (\r\n) to:
- Inject arbitrary HTTP headers
- Terminate the HTTP request prematurely and smuggle raw data to non-HTTP services (Redis, Memcached, Elasticsearch)
The vulnerability exists because undici writes the upgrade value directly to the socket without validating for invalid header characters:
// lib/dispatcher/client-h1.js:1121
if (upgrade) {
header +=
connection: upgrade\r\nupgrade: ${upgrade}\r\n}
Details
- Affected product:
- AlmaLinux 9.2 ESU , TuxCare 9.6 ESU , astro , miniflare , remix , undici , workers-sdk
- Affected packages:
- undici (+36 more)