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

Severity: high (CVSS 7.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.5% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-08-30 · updated 2026-09-10
Weakness: CWE-20

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

ChatGPTNextWeb NextChat: from 2.15.8 through 2.16.1

References

https://github.com/ChatGPTNextWeb/NextChat
https://github.com/ChatGPTNextWeb/NextChat/blob/v2.16.1/app/api/proxy.ts
https://github.com/ChatGPTNextWeb/NextChat/issues/6814
https://www.vulncheck.com/advisories/nextchat-2.15.8-through-2.16.1-openai-api-key-disclosure
https://github.com/ChatGPTNextWeb/NextChat/issues/6814

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