CVE-2026-82639: Chatgptnextweb Nextchat

High severity, CVSS 7.5. EPSS: 0.5% chance of exploitation in the next 30 days.

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.

Affected products

• Chatgptnextweb Nextchat: from 2.15.8, up to and including 2.16.1

Published 2026-08-30. Last modified 2026-09-10.