Vulnerability · Published Sep 18, 2026 · Assigned by VulnCheck

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

Critical 9.8

In plain English

A critical-severity missing authentication in LightLLM from ModelTC. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.8% (higher than 55% of all known vulnerabilities).

Severity (CVSS 3.1)9.8Critical

Exploit odds (30 days)0.8%top 44.5% of all CVEs

Exploited in the wildNo reportsCISA SSVC: poc

Attack toolingNoneno public tooling known

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.

Affected products (as reported)

Vendor	Product	Versions
ModelTC	LightLLM	0 – through 1.2.0

Weakness: CWE-306 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

References

GitHub Issue #1576 issue-tracking
https://github.com/ModelTC/LightLLM product
https://github.com/ModelTC/lightllm/blob/v1.2.0/lightllm/server/api_http_pd.py#L26-L36 technical-description
https://github.com/ModelTC/lightllm/blob/v1.2.0/lightllm/server/httpserver_for_pd_master/manager.py#L714-L749 technical-description
https://github.com/ModelTC/lightllm/blob/v1.2.0/lightllm/server/httpserver_for_pd_master/manager.py#L691-L698 technical-description
https://github.com/ModelTC/lightllm/blob/v1.2.0/lightllm/server/api_http.py#L198-L205 technical-description
VulnCheck Advisory: LightLLM through 1.2.0 Missing Authentication in PD Master /pd_register WebSocket Endpoint third-party-advisory