Quick answers
- Is CVE-2026-82639 exploited in the wild?
- No. Junglewise Threat Intelligence has no report of CVE-2026-82639 being exploited in the wild.
- How severe is CVE-2026-82639?
- High severity, with a CVSS score of 7.5, published 30 August 2026.
- Which products and versions are affected?
- ChatGPTNextWeb NextChat 2.15.8 through 2.16.1.
- Is there a fix for CVE-2026-82639?
- No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.
- How is CVE-2026-82639 attacked?
- It is attacked over the network.
- Am I affected by CVE-2026-82639?
- Check whether anything you run is named in the advisory. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.
Technical details
The vulnerability is an improper URL validation flaw in the proxy endpoint (app/api/proxy.ts). The code uses substring matching (`baseUrl?.includes("api.openai.com")`) to validate the x-base-url header instead of proper hostname parsing. This allows an attacker to bypass validation by sending any URL containing "api.openai.com" (e.g., "http://attacker.com/api.openai.com"), and the server will forward the OpenAI API key in the Authorization header to the attacker's server. The attack is network-accessible and requires no authentication or user interaction beyond crafting a specially-formed request. Patches are available in versions after 2.16.1.
Affected products
- ChatGPTNextWeb NextChat 2.15.8 through 2.16.1
Timeline
- 2026-08-30: disclosed