# CVE-2026-93839: LightLLM through 1.2.0 Missing Authentication in PD Master /pd_register WebSocket Endpoint


- **Severity:** Critical 9.3 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Fix available:** No
- **Published:** 18 Sep 2026
- **Updated:** 24 Sep 2026
- **Also known as:** GHSA-644q-7756-5g89

## What is CVE-2026-93839?

CVE-2026-93839 is a critical vulnerability in ModelTC LightLLM, published on 18 Sep 2026. 

### Official description

LightLLM through 1.2.0 contains an authentication bypass vulnerability in the /pd_register WebSocket endpoint that allows unauthenticated attackers to register arbitrary nodes by supplying crafted JSON without peer address validation. Attackers can disclose full user prompts routed to their socket, trigger denial of service by replacing legitimate nodes, or make the PD Master issue requests to internal network addresses.

Weakness: CWE-306 (Missing Authentication for Critical Functionality)

## Which versions are affected by CVE-2026-93839?


## How do I fix CVE-2026-93839?

No fix has been published for CVE-2026-93839 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-93839 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-93839 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-93839 and fix it if it is affected.

What it is: CVE-2026-93839 is a critical vulnerability in ModelTC LightLLM, published on 18 Sep 2026. 
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-93839 exists.

Affected product: ModelTC LightLLM. 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-2026-93839/ (Markdown: https://insights.sbomify.com/CVE-2026-93839/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-93839
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-93839
- OSV: https://osv.dev/vulnerability/CVE-2026-93839

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-93839/
Summaries are generated and may contain mistakes; the official description above is the record.