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

> Attackers can steal the server's OpenAI API key by exploiting improper URL validation in the proxy endpoint of NextChat.

- **Severity:** High 8.7 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 30 Aug 2026
- **Updated:** 24 Sep 2026
- **Also known as:** GHSA-87fx-h8m6-gxwv

## What is CVE-2026-82639?

CVE-2026-82639 is a high-severity vulnerability in ChatGPTNextWeb NextChat, published on 30 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### 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.

Weakness: CWE-20 (Improper Input Validation)

## Which versions are affected by CVE-2026-82639?


## How do I fix CVE-2026-82639?

No fix has been published for CVE-2026-82639 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-82639 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-82639 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-82639 and fix it if it is affected.

What it is: CVE-2026-82639 is a high-severity vulnerability in ChatGPTNextWeb NextChat, published on 30 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-82639 exists.

Affected product: ChatGPTNextWeb NextChat. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-82639/ (Markdown: https://insights.sbomify.com/CVE-2026-82639/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-82639
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-82639
- OSV: https://osv.dev/vulnerability/CVE-2026-82639

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-82639/
Summaries are generated and may contain mistakes; the official description above is the record.