CRLF injection in undici - CVE-2026-1527
Published: April 24, 2026
Vulnerability identifier: #VU127577
CSH Severity: Low
CVSS v4.0: CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:A/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N/E:U/U:Clear
CVE-ID: CVE-2026-1527
CWE-ID: CWE-93
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vendor: Node.js
Affected software:
undici
undici
Detailed vulnerability description
The vulnerability allows a remote attacker to inject arbitrary HTTP headers and smuggle raw data to non-HTTP services.
The vulnerability exists due to improper neutralization of CRLF sequences in the upgrade option of client.request() when processing user-controlled input. A remote attacker can supply a specially crafted upgrade value to inject arbitrary HTTP headers and smuggle raw data to non-HTTP services.
User interaction is required because an application must pass user-controlled input to the upgrade option.
How to mitigate CVE-2026-1527
Install security update from vendor's website.