CVE-2026-1525

A flaw was found in undici, a Node.js HTTP/1.1 client. A remote attacker could exploit this vulnerability by sending HTTP/1.1 requests that include duplicate Content-Length headers with different casing (e.g., "Content-Length" and "content-length"). This can lead to HTTP Request Smuggling, a technique where an attacker sends an ambiguous request that is interpreted differently by a proxy and a backend server. Successful exploitation could result in unauthorized access, cache poisoning, or credential hijacking. It may also cause a Denial of Service (DoS) if strict HTTP parsers reject the malformed requests.

Moderate impact. A flaw in the undici Node.js HTTP/1.1 client allows for HTTP Request Smuggling or Denial of Service. This can occur in Red Hat products that use undici and process HTTP requests where user-controlled header names are not case-normalized, or headers are passed as flat arrays.

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.

Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base or stability.