Vulnerability · Published Aug 30, 2026 · Assigned by VulnCheck

CVE-2026-82639NextChat 2.15.8 through 2.16.1 OpenAI API Key Disclosure

High 7.5

In plain English

A high-severity improper input validation in NextChat from ChatGPTNextWeb. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.5% (higher than 44% of all known vulnerabilities).

Severity (CVSS 3.1)7.5High

Exploit odds (30 days)0.5%top 56.4% of all CVEs

Exploited in the wildNo reportsCISA SSVC: poc

Attack toolingNoneno public tooling known

Official description

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 (as reported)

Vendor	Product	Versions
ChatGPTNextWeb	NextChat	2.15.8 – through 2.16.1

Weakness: CWE-20 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

References

GitHub Issue #6814 issue-tracking
https://github.com/ChatGPTNextWeb/NextChat product
https://github.com/ChatGPTNextWeb/NextChat/blob/v2.16.1/app/api/proxy.ts technical-description
VulnCheck Advisory: NextChat 2.15.8 through 2.16.1 OpenAI API Key Disclosure third-party-advisory