Auth bypass in Modeltc Lightllm
CVE-2026-93839
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.
Vulnerability class: Broken Authentication
Published · last modified .
CVSS v3 metric
CVSS v3 base score 9.8 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.
EPSS exploit prediction
EPSS: 0.008 (55.3th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 55th percentile — 55.3% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.008 · newest: 0.008 · change: 0.000
Affected products
Weakness classification (CWE)
References
- github.com/ModelTC/LightLLM/issues/1576 (issue-tracking)
- github.com/ModelTC/LightLLM (product)
- github.com/ModelTC/lightllm/blob/v1.2.0/lightllm/server/api_http_pd.py (technical-description)
- github.com/ModelTC/lightllm/blob/v1.2.0/lightllm/server/httpserver_for_pd_maste… (technical-description)
- github.com/ModelTC/lightllm/blob/v1.2.0/lightllm/server/httpserver_for_pd_maste… (technical-description)
- github.com/ModelTC/lightllm/blob/v1.2.0/lightllm/server/api_http.py (technical-description)
- www.vulncheck.com/advisories/lightllm-through-1.2.0-missing-authentication-in-p… (third-party-advisory)
Frequently asked questions
- What is CVE-2026-93839?
- CVE-2026-93839 is a critical-severity vulnerability in Modeltc Lightllm, classified under Missing Authentication for Critical Function. CVSS score: 9.8/10. Published 2026-09-18.
- How severe is CVE-2026-93839?
- Critical severity. CVSS v3 base score is 9.8 out of 10.