Critical Authentication

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

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.

Published Sep 18, 2026 · Updated Oct 15, 2026 · Sources: NIST National Vulnerability Database, CVE Program (cve.org) e CISA ADP · CNA: VulnCheck

Low

Who exploits it and how urgent it is

A 0–100 score combining confirmed exploitation, ransomware and APT use, public exploits, EPSS and severity.

No exploitation signal in the sources consulted so far.

How the score was calculated

Technical severity (critical)+10
CISA SSVC: exploitation "poc"+5
Automatable exploitation (SSVC)+3

The score orders the patch queue; it does not replace your asset context (internet exposure, criticality, compensating controls).

Triage

Is it exploited, how likely is exploitation, what does it touch, and how severe do the sources call it.

Exploitation

Not confirmed

Not in CISA KEV — an absence of record, not proof it is unexploited.

EPSS FIRST

—

No EPSS score.

Affects

ModelTC

LightLLM

CVSS base

9.8

Critical · 2 source(s)

CISA SSVC assessment CISA

Three decision points CISA publishes for the CVEs it assesses (SSVC 2.0.3). A stakeholder decision, not a severity score.

Exploitation

Proof of concept

none · proof-of-concept · active

Automatable

Yes

can an attacker script the kill-chain steps

Technical impact

Total

partial · total control of the vulnerable component

Remediation

Fixes and mitigations documented by the sources — linked to the original advisory.

No fix documented by the sources we poll. That does not mean none exists: check the vendor advisory.

First 24 hours

Ordered from the record’s own fields — exposure first, because you cannot patch what you have not found. A rule-generated starting point.

Identify exposed assets running the affected vendor/product/version combinations (ModelTC LightLLM).
The attack is network-based and needs no privileges: restrict exposure (ACLs, VPN, WAF) until patched.
No fix documented in the sources: reduce exposure and monitor the vendor advisory.
Search available logs for exploit probes matching the vulnerability class (authentication), errors and authentication anomalies.

Affected scope

Vendor, product and versions as the sources word them.

Vendor	Product	Versions	Status	Source
ModelTC	LightLLM	≤ 1.2.0	Vulnerable	CVE Program (cve.org) e CISA ADP

Attack characteristics

The CVSS vector, decoded. It describes the attack, not your exposure to it.

Attack vector

Network

Attack complexity

Low

Privileges required

None

User interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

High

Availability

High

Every base score collected

Sources score independently and may disagree; each row says who scored it and under which version.

Score	Version	Severity	Expl.	Impact	Scored by
9.3	CVSS 4.0	Critical	—	—	disclosure@vulncheck.com via NIST National Vulnerability Database
9.3	CVSS 4.0	Critical	—	—	VulnCheck via CVE Program (cve.org) e CISA ADP
9.8	CVSS 3.1	Critical	3.9	5.9	disclosure@vulncheck.com via NIST National Vulnerability Database
9.8	CVSS 3.1	Critical	—	—	VulnCheck via CVE Program (cve.org) e CISA ADP

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H (score shown at the top: disclosure@vulncheck.com)

Weakness MITRE

Weakness class according to MITRE’s CWE catalog.

CWE-306 · Missing Authentication for Critical Function

Other CVEs with this weakness →

Detection

Read off the CVSS vector and the weakness class. Starting points, not tested rules.

Prioritize edge telemetry for the network-reachable component (proxy, WAF, IDS/IPS).
Review authentication logs: logins without MFA, anomalous sessions and recently created accounts.

web/proxy/WAF logsnetwork IDS/IPSauthentication logs

Timeline

What happened to this CVE, newest first.

2026
Affected products added · modeltc/lightllm
Oct 15, 2026 · CVE Program (cve.org) e CISA ADP
SSVC assessment updated
Oct 15, 2026 · CVE Program (cve.org) e CISA ADP
Record published
Oct 15, 2026
CVSS changed · 9.8
Oct 15, 2026 · NIST National Vulnerability Database
Source status changed · → Awaiting Analysis
Oct 15, 2026 · NIST National Vulnerability Database
Record created in this database
Oct 15, 2026 · NIST National Vulnerability Database
CVE published
Sep 18, 2026 · VulnCheck

Source activity

Repeated readings are counted rather than listed.

1× Official description updated · Oct 15, 2026 – Oct 15, 2026

References

7 on the record

github.com/ModelTC/lightllm/blob/v1.2.0/lightllm/server/api_http_pd.py
technical-description, NIST National Vulnerability Database
github.com/ModelTC/LightLLM/issues/1576
issue-tracking, NIST National Vulnerability Database
github.com/ModelTC/lightllm/blob/v1.2.0/lightllm/server/httpserver_for_pd_master
technical-description, NIST National Vulnerability Database
github.com/ModelTC/lightllm/blob/v1.2.0/lightllm/server/httpserver_for_pd_master
technical-description, NIST National Vulnerability Database
github.com/ModelTC/lightllm/blob/v1.2.0/lightllm/server/api_http.py
technical-description, NIST National Vulnerability Database
github.com/ModelTC/LightLLM
product, NIST National Vulnerability Database
www.vulncheck.com/advisories/lightllm-through-1.2.0-missing-authentication-in-pd-master
third-party-advisory, NIST National Vulnerability Database

Elsewhere on this site

ModelTC
every CVE for this vendor

Authentication
same class

CWE-306
other pages naming this weakness

Related CVEs (same products)

High CVE-2026-111160 LightLLM through 1.2.0 Unauthenticated DoS via pd_kv_trans_params Deserialization 9h
Critical CVE-2026-103395 LightLLM through 1.2.0 Unauthenticated Remote Code Execution via Visual-Only RPyC Service 15d
Medium CVE-2026-103243 LightLLM through 1.2.0 Server-Side Request Forgery via multimodal endpoints 15d
High CVE-2026-103270 LightLLM through 1.2.0 Missing Authentication on RL Control Routes 15d
Critical CVE-2026-103040 LightLLM through 1.2.0 Unauthenticated Remote Code Execution via Router Profiler RPyC Service 16d
Critical CVE-2026-103041 LightLLM through 1.2.0 Unauthenticated Remote Code Execution via Embed Cache RPyC Service 16d

Not in any source we poll

Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.

No FIRST EPSS score.
No fixed version, patch or mitigation documented.
No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
No exploit packet captures, log samples, or incident case IDs supplied.

Answered from this record

Text assembled only from the fields above — no additional claims.

What should defenders know first?

CVE-2026-93839 is "LightLLM through 1.2.0 Missing Authentication in PD Master /pd_register WebSocket Endpoint", rated Critical. It affects LightLLM (ModelTC); versions are in the scope table. It is not in CISA KEV, which does not rule out exploitation. CVSS 9.8 describes technical severity. First verify whether exposed or business-critical assets run the affected versions, apply vendor fixes or mitigations, and preserve logs for review.

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