CVE-2026-90938Public exploitNetwork attack vectorHinoki check available

Message-plane compromise via unauthenticated plugin registration

Published Sep 14, 2026 · Updated Sep 14, 2026

Missing authentication in LangBot's plugin runtime through 0.4.17 allows remote attackers to compromise bot messaging via WebSocket. The REGISTER_PLUGIN handler skips key verification when plugin_debug_key is empty, while the runtime binds the debug server to 0.0.0.0 and broadcasts all message events to every initialized plugin. Network access to port 5401 is sufficient without credentials, enabling plaintext message access, forged bot replies, malicious tool registration, and persistent installation blocking.

CVSS severity8.6
High
EPSS probability0.35%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkAvailable
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Summary

What happened

Missing authentication in LangBot's plugin runtime through 0.4.17 allows remote attackers to compromise bot messaging via WebSocket. The REGISTER_PLUGIN handler skips key verification when plugin_debug_key is empty, while the runtime binds the debug server to 0.0.0.0 and broadcasts all message events to every initialized plugin. Network access to port 5401 is sufficient without credentials, enabling plaintext message access, forged bot replies, malicious tool registration, and persistent installation blocking.

The record

CVE
CVE-2026-90938
Published
Sep 14, 2026
Updated
Sep 14, 2026
Vendor
LangBot
Product
LangBot
Classifications
CWE-345, CWE-306, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Sep 14, 2026CVE publishedPublication date reported by the CVE source.
  2. Sep 14, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=0 <=0.4.17

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

LangBot · LangBotversion=0 <=0.4.17

Published CVSS scores

8.6GitHubCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:L

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-345Insufficient Verification of Data Authenticity
CWE-306Missing Authentication for Critical Function
T1190Exploit Public-Facing Application

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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