ChatGPTNextWeb NextChat up to 2.16.1 Proxy Endpoint x-base-url improper authorization

Summaryinfo

A vulnerability was found in ChatGPTNextWeb NextChat up to 2.16.1 and classified as problematic. This impacts an unknown function of the component Proxy Endpoint. Such manipulation of the argument x-base-url leads to improper authorization. This vulnerability is uniquely identified as CVE-2026-82639. The attack can be launched remotely. No exploit exists.

Detailsinfo

A vulnerability was found in ChatGPTNextWeb NextChat up to 2.16.1. It has been rated as problematic. Affected by this issue is an unknown code of the component Proxy Endpoint. The manipulation of the argument x-base-url with an unknown input leads to a improper authorization vulnerability. Using CWE to declare the problem leads to CWE-285. The product does not perform or incorrectly performs an authorization check when an actor attempts to access a resource or perform an action. Impacted is confidentiality. CVE summarizes:

NextChat versions from 2.15.8 through 2.16.1 contain an improper URL validation vulnerability in the proxy endpoint that allows attackers to obtain the server's OpenAI API key. The x-base-url header is validated using substring matching instead of hostname parsing, allowing any URL containing 'api.openai.com' to pass validation and receive the server's credentials in the Authorization header.

The advisory is available at github.com. This vulnerability is handled as CVE-2026-82639 since 08/30/2026. The exploitation is known to be easy. The attack may be launched remotely. No form of authentication is required for exploitation. Technical details are known, but there is no available exploit. The structure of the vulnerability defines a possible price range of USD $0-$5k at the moment (estimation calculated on 08/30/2026). This vulnerability is assigned to T1548.002 by the MITRE ATT&CK project.

There is no information about possible countermeasures known. It may be suggested to replace the affected object with an alternative product.

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Productinfo

Type

• Chat Software

Vendor

• ChatGPTNextWeb

Name

• NextChat

Version

• 2.16.0
• 2.16.1

Website

• Product: https://github.com/ChatGPTNextWeb/NextChat/

CPE 2.3info

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CPE 2.2info

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