CVE-2026-1525

  1. OpenCVE
  2. Vulnerabilities (CVE)
  3. CVE-2026-1525
Undici allows duplicate HTTP Content-Length headers when they are provided in an array with case-variant names (e.g., Content-Length and content-length). This produces malformed HTTP/1.1 requests with multiple conflicting Content-Length values on the wire. Who is impacted: * Applications using undici.request(), undici.Client, or similar low-level APIs with headers passed as flat arrays * Applications that accept user-controlled header names without case-normalization Potential consequences: * Denial of Service: Strict HTTP parsers (proxies, servers) will reject requests with duplicate Content-Length headers (400 Bad Request) * HTTP Request Smuggling: In deployments where an intermediary and backend interpret duplicate headers inconsistently (e.g., one uses the first value, the other uses the last), this can enable request smuggling attacks leading to ACL bypass, cache poisoning, or credential hijacking

6.5 /10

CVSS v3 : MEDIUM

V3 Legend

Vector :

Exploitability : 3.9 / Impact : 2.5

Attack Vector NETWORK

Attack Complexity LOW

Privileges Required NONE

User Interaction NONE

Confidentiality Impact NONE

Integrity Impact LOW

Availability Impact LOW

Scope UNCHANGED

References
Link Resource
https://cna.openjsf.org/security-advisories.html Vendor Advisory
https://cwe.mitre.org/data/definitions/444.html Technical Description
https://github.com/nodejs/undici/security/advisories/GHSA-2mjp-6q6p-2qxm Mitigation Vendor Advisory
https://hackerone.com/reports/3556037 Permissions Required
https://www.rfc-editor.org/rfc/rfc9110.html#section-8.6 Technical Description
Configurations

Configuration 1 (hide)

OR cpe:2.3:a:nodejs:undici:*:*:*:*:*:node.js:*:*
cpe:2.3:a:nodejs:undici:*:*:*:*:*:node.js:*:*
History

19 Mar 2026, 17:29

Type Values Removed Values Added
First Time Nodejs undici
Nodejs
CPE cpe:2.3:a:nodejs:undici:*:*:*:*:*:node.js:*:*
Summary
  • (es) Undici permite encabezados HTTP Content-Length duplicados cuando se proporcionan en un array con nombres que varían en mayúsculas/minúsculas (p. ej., Content-Length y content-length). Esto produce solicitudes HTTP/1.1 malformadas con múltiples valores Content-Length conflictivos en la red. Quiénes son los afectados: * Aplicaciones que utilizan undici.request(), undici.Cliente, o APIs de bajo nivel similares con encabezados pasados como arrays planos * Aplicaciones que aceptan nombres de encabezado controlados por el usuario sin normalización de mayúsculas/minúsculas Posibles consecuencias: * Denegación de Servicio: Analizadores HTTP estrictos (proxies, servidores) rechazarán las solicitudes con encabezados Content-Length duplicados (400 Solicitud Incorrecta) * Contrabando de Solicitudes HTTP: En implementaciones donde un intermediario y un backend interpretan encabezados duplicados de manera inconsistente (p. ej., uno usa el primer valor, el otro usa el último), esto puede habilitar ataques de contrabando de solicitudes que conducen a la omisión de ACL, envenenamiento de caché o secuestro de credenciales
References () https://cna.openjsf.org/security-advisories.html - () https://cna.openjsf.org/security-advisories.html - Vendor Advisory
References () https://cwe.mitre.org/data/definitions/444.html - () https://cwe.mitre.org/data/definitions/444.html - Technical Description
References () https://github.com/nodejs/undici/security/advisories/GHSA-2mjp-6q6p-2qxm - () https://github.com/nodejs/undici/security/advisories/GHSA-2mjp-6q6p-2qxm - Mitigation, Vendor Advisory
References () https://hackerone.com/reports/3556037 - () https://hackerone.com/reports/3556037 - Permissions Required
References () https://www.rfc-editor.org/rfc/rfc9110.html#section-8.6 - () https://www.rfc-editor.org/rfc/rfc9110.html#section-8.6 - Technical Description

12 Mar 2026, 20:16

Type Values Removed Values Added
New CVE
Information

Published : 2026-03-12 20:16

Updated : 2026-03-19 17:29

NVD link : CVE-2026-1525

Mitre link : CVE-2026-1525

CVE.ORG link : CVE-2026-1525

JSON object : View

Products Affected

nodejs

  • undici
CWE
CWE-444

Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling')