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CVE-2026-90938— LangBot through 0.4.17 Unauthenticated Plugin Registration via WebSocket

Quick assessment

Affected
langbot-app LangBot
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

LangBot是LangBot团队开源的一个大模型即时通信机器人开发平台。 LangBot 0.4.17及之前版本存在授权问题漏洞，该漏洞源于在0.0.0.0:5401的/plugin/ws启动调试WebSocket服务器，其身份验证依赖默认空字符串且从未设置的plugin_debug_key，导致密钥检查被完全跳过；远程攻击者无需凭据即可注册任意“debug plugin”，接收所有IM消息事件完整上下文（包括私聊、消息链和用户/发送者ID明文），并可注入伪造回复、以任意已配置机器人发送消息、枚举机器人

CVSS 8.6 · High EPSS 0.57% · P47

Affected Version Matrix 1

VendorProduct Version RangeStatus
langbot-app LangBot ≤ 0.4.17 affected
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I. Basic Information for CVE-2026-90938

Vulnerability Information
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Vulnerability Title
LangBot through 0.4.17 Unauthenticated Plugin Registration via WebSocket
Source: CVE Program / CVE List V5
Vulnerability Description
LangBot's plugin runtime (pip package langbot_plugin) through 0.4.17 starts a debug WebSocket server on 0.0.0.0:5401 (/plugin/ws) whose authentication is gated on plugin_debug_key, which defaults to an empty string and is never set by the upstream repository, Docker image, or docker-compose (which additionally publishes port 5401 to the host); the key check is therefore skipped entirely. Any remote attacker able to reach the port can register an arbitrary "debug plugin" without credentials. Because events are broadcast to all initialized plugins without filtering, the attacker's plugin receives the full context of every IM message event (including private chats, message chains, and user/sender IDs in plaintext) and can inject forged replies, send messages as any configured bot, enumerate bot UUIDs, invoke configured LLM models, read knowledge-base contents, and register malicious tools that feed every user's LLM pipeline. Registering with "prod_mode": true causes later legitimate installations of a plugin with the same author/name to be rejected, resulting in persistent denial of service. No patched version was available at the time of publication.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:L
Source: CVE Program / CVE List V5
Vulnerability Type
关键功能的认证机制缺失
Source: CVE Program / CVE List V5
Vulnerability Title
LangBot 授权问题漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
LangBot是LangBot团队开源的一个大模型即时通信机器人开发平台。 LangBot 0.4.17及之前版本存在授权问题漏洞，该漏洞源于在0.0.0.0:5401的/plugin/ws启动调试WebSocket服务器，其身份验证依赖默认空字符串且从未设置的plugin_debug_key，导致密钥检查被完全跳过；远程攻击者无需凭据即可注册任意“debug plugin”，接收所有IM消息事件完整上下文（包括私聊、消息链和用户/发送者ID明文），并可注入伪造回复、以任意已配置机器人发送消息、枚举机器人
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
langbot-app LangBot 0 ~ 0.4.17 -

II. Public POCs for CVE-2026-90938

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III. Intelligence Information for CVE-2026-90938

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Vendor Advisories for CVE-2026-90938 (2)

IV. Related Vulnerabilities

Same product: LangBot
Same vendor: langbot-app
Same weakness: CWE-306