CVE-2026-1527

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` }

The following products are affected by CVE-2026-1527 vulnerability.

Here, you will find a curated list of external links that provide in-depth information to CVE-2026-1527.

URL	Resource
https://cna.openjsf.org/security-advisories.html
https://github.com/nodejs/undici/security/advisories/GHSA-4992-7rv2-5pvq
https://hackerone.com/reports/3487198
https://nvd.nist.gov/vuln/detail/CVE-2026-1527
https://www.cve.org/CVERecord?id=CVE-2026-1527