Node.js Undici up to 6.28.0/7.29.1/8.10.2 Retry Interceptor response splitting

Summaryinfo

A vulnerability categorized as problematic has been discovered in Node.js Undici up to 6.28.0/7.29.1/8.10.2. This issue affects some unknown processing of the component Retry Interceptor. Executing a manipulation can lead to response splitting. This vulnerability is handled as CVE-2026-18540. The attack can be executed remotely. There is not any exploit available. It is advisable to upgrade the affected component.

Detailsinfo

A vulnerability classified as problematic was found in Node.js Undici up to 6.28.0/7.29.1/8.10.2. This vulnerability affects an unknown functionality of the component Retry Interceptor. The manipulation with an unknown input leads to a response splitting vulnerability. The CWE definition for the vulnerability is CWE-113. The product receives data from an HTTP agent/component (e.g., web server, proxy, browser, etc.), but it does not neutralize or incorrectly neutralizes CR and LF characters before the data is included in outgoing HTTP headers. As an impact it is known to affect integrity. CVE summarizes:

undici's retry interceptor can append the body of a ranged retry response to bytes already delivered from an earlier partial response while still presenting the original response's status and headers. This happens when an upstream server delivers part of a body without a trustworthy resume checkpoint, for example a non-success response whose headers were already sent or a partial-content response with an unusable content range, then closes the connection and answers the resumed range request with more bytes. As a result the response body can be longer than the Content-Length that the application observes. An application that relays such a response to a downstream HTTP/1.1 peer without normalizing the framing can emit a body that exceeds the forwarded Content-Length, and the excess bytes can be interpreted as the start of a following response, which enables downstream response splitting or desynchronization. Exploitation requires an attacker-controlled upstream server and an application that forwards the response through a framing-sensitive path. This affects undici versions before 6.28.1, from 7.0.0 up to 7.29.1, and from 8.0.0 up to 8.10.2. Users should upgrade to undici 6.28.1, 7.29.1, or 8.10.2.

The advisory is available at github.com. This vulnerability was named CVE-2026-18540 since 07/31/2026. The exploitation appears to be easy. The attack can be initiated remotely. No form of authentication is required for a successful exploitation. The technical details are unknown and an exploit is not available.

The vulnerability scanner Nessus provides a plugin with the ID 343100 (Linux Distros Unpatched Vulnerability : CVE-2026-18540), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 6.28.1, 7.29.1 or 8.10.2 eliminates this vulnerability.

The vulnerability is also documented in the vulnerability database at Tenable (343100). If you want to get best quality of vulnerability data, you may have to visit VulDB.

Productinfo

Type

• JavaScript Library

Vendor

• Node.js

Name

• Undici

Version

• 6.0
• 6.1
• 6.2
• 6.3
• 6.4
• 6.5
• 6.6
• 6.7
• 6.8
• 6.9
• 6.10
• 6.11
• 6.12
• 6.13
• 6.14
• 6.15
• 6.16
• 6.17
• 6.18
• 6.19
• 6.20
• 6.21
• 6.22
• 6.23
• 6.24
• 6.25
• 6.26
• 6.27
• 6.28.0
• 7.29.0
• 7.29.1
• 8.10.0
• 8.10.1
• 8.10.2

License

• open-source

CPE 2.3info

• 🔒
• 🔒
• 🔒

CPE 2.2info

• 🔒
• 🔒
• 🔒

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Entryinfo

If you want to get best quality of vulnerability data, you may have to visit VulDB.

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