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CVE-2026-1527

4.6 · MEDIUM

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…

Published Mar 12, 2026CWE-93EPSS 0.28%

Overview

CVE-2026-1527 is a medium-severity vulnerability. It was published on March 12, 2026 and has a CVSS 3.1 base score of 4.6 (MEDIUM).

This vulnerability has a CVSS 3.1 base score of 4.6, rated MEDIUM. It can be exploited remotely over the network. Some level of privileges is required for exploitation.

Technical 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`

}

Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

References

Refcna.openjsf.org/security-advisories.htmlGitHubgithub.com/nodejs/undici/security/advisories/GHSA-4992-7rv2-5pvqRefhackerone.com/reports/3487198

How CyberStrike helps

Frequently asked questions

What is CVE-2026-1527?

CVE-2026-1527 is a medium-severity vulnerability. It was published on March 12, 2026 and has a CVSS 3.1 base score of 4.6 (MEDIUM).

How severe is CVE-2026-1527?

This vulnerability has a CVSS 3.1 base score of 4.6, rated MEDIUM. It can be exploited remotely over the network. Some level of privileges is required for exploitation.

How do I fix or remediate CVE-2026-1527?

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

How can CyberStrike help with CVE-2026-1527?

CyberStrike is an open-source, AI-augmented pentesting engine. Rather than flag a version number, it tests whether an issue like CVE-2026-1527 is actually reachable in your own applications and APIs, then verifies each finding before reporting it. That tells you if the weakness is a real, exploitable risk in your environment or a false positive you can safely deprioritize.

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