CVE-2026-1527

Description

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` }

CVSS Metrics

• v3.1•MEDIUM•Score: 4.6CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:L/I:L/A:N

EPSS Trends

Current EPSS score: 0.26%• Percentile: 17%

Techniques & Countermeasures

• CWE-93•Improper Neutralization of CRLF Sequences ('CRLF Injection')

  The product uses CRLF (carriage return line feeds) as a special element, e.g. to separate lines or records, but it does not neutralize or incorrectly neutralizes CRLF sequences from inputs.

Affected Systems

• nodejs•undici

  < 6.24.0 | ≥ 7.0.0, < 7.24.0

• Npm•undici

  < 6.24.0 | ≥ 7.0.0, < 7.24.0

• undici•undici

  < 6.24.0; 7.0.0 < 7.24.0

References (5)

• https://github.com/nodejs/undici/security/advisories/GHSA-4992-7rv2-5pvq
• https://hackerone.com/reports/3487198
• https://cna.openjsf.org/security-advisories.html
• https://nvd.nist.gov/vuln/detail/CVE-2026-1527
• https://github.com/nodejs/undici