CVE-2026-1527

Name: CVE-2026-1527
Creator: NVD / NIST
Published: 2026-03-12T21:16:25.137+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

MEDIUMCVSS 4.6/10EPSS 0.26%

Last modified Jun 17, 2026

CVE-2026-1527 is a medium-severity vulnerability rated 4.6/10 on the CVSS scale. 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` }. EPSS estimates a 0.26% chance of exploitation in the next 30 days.

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` }

Metrics

CVSS 3.1

4.6/10

CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:L/I:L/A:N

EPSS Probability

0.26%

16.9th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-93

Affected Software

Vendor	Product	Versions
Nodejs	Undici	< 6.24.0
Nodejs	Undici	>= 7.0.0, < 7.24.0

References

https://cna.openjsf.org/security-advisories.htmlVendor Advisory
https://github.com/nodejs/undici/security/advisories/GHSA-4992-7rv2-5pvqMitigation, Patch, Vendor Advisory
https://hackerone.com/reports/3487198Permissions Required

Timeline

Published: Mar 12, 2026
Last Modified: Jun 17, 2026
Status: Analyzed

Frequently Asked Questions

What is CVE-2026-1527?

How severe is CVE-2026-1527?

CVE-2026-1527 has a CVSS score of 4.6/10 (MEDIUM severity). The EPSS model estimates a 0.26% probability of exploitation in the next 30 days.

How do I fix CVE-2026-1527?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2026-1527?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST