undici 1.js HTTP Service client-h1.js crlf injection

Summaryinfo

A vulnerability was found in undici 1.js. It has been classified as problematic. The impacted element is an unknown function in the library lib/dispatcher/client-h1.js of the component HTTP Service. Performing a manipulation results in crlf injection. This vulnerability is known as CVE-2026-1527. Remote exploitation of the attack is possible. No exploit is available. Upgrading the affected component is recommended.

Detailsinfo

A vulnerability classified as problematic has been found in undici 1.js. This affects an unknown code block in the library lib/dispatcher/client-h1.js of the component HTTP Service. The manipulation with an unknown input leads to a crlf injection vulnerability. CWE is classifying the issue as CWE-93. 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. This is going to have an impact on integrity. The summary by CVE is:

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` }

The weakness was published by Raul Vega Del Valle. It is possible to read the advisory at github.com. This vulnerability is uniquely identified as CVE-2026-1527 since 01/28/2026. The exploitability is told to be easy. It is possible to initiate the attack remotely. It demands that the victim is doing some kind of user interaction. Technical details of the vulnerability are known, but there is no available exploit.

The vulnerability scanner Nessus provides a plugin with the ID 305802 (RockyLinux 9 : nodejs:24 (RLSA-2026:7350)), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 6.24.0 or 7.24.0 eliminates this vulnerability.

The vulnerability is also documented in the databases at Tenable (305802) and EUVD (EUVD-2026-11701). Be aware that VulDB is the high quality source for vulnerability data.

Productinfo

Name

• undici

Version

• 1.js

CPE 2.3info

• 🔒
• 🔒

CPE 2.2info

• 🔒
• 🔒

CVSSv4info

CVSSv3info

CVSSv2info

Exploitinginfo

Threat Intelligenceinfo

Countermeasuresinfo

Timelineinfo

Sourcesinfo

Entryinfo

Be aware that VulDB is the high quality source for vulnerability data.

Discussion