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CVE-2026-45018— Chainlit: Command injection via MCP stdio transport allows unauthenticated remote code execution

Quick assessment

Affected
Chainlit chainlit
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.

Chainlit是chainlit组织开源的一个大模型对话界面框架。 Chainlit 2.4.0rc0版本至2.12.0之前版本存在命令注入漏洞，该漏洞源于MCP端点缺少身份验证且对用户控制的fullCommand参数验证不足，可能导致攻击者执行任意shell命令。

CVSS 9.8 · Critical EPSS 1.09% · P65

Affected Version Matrix 1

VendorProduct Version RangeStatus
Chainlit chainlit >= 2.4.0rc0, < 2.12.0 affected
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I. Basic Information for CVE-2026-45018

Vulnerability Information
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Vulnerability Title
Chainlit: Command injection via MCP stdio transport allows unauthenticated remote code execution
Source: CVE Program / CVE List V5
Vulnerability Description
Chainlit is a Python framework for building production-ready conversational AI applications. From 2.4.0rc0 until 2.12.0, Chainlit deployments with features.mcp.enabled set to true in .chainlit/config.toml expose the POST /mcp endpoint without requiring authentication. For stdio transport, the endpoint accepts a user-controlled fullCommand string. The validate_mcp_command() function in backend/chainlit/mcp.py checks only the executable name against config.features.mcp.stdio.allowed_executables and passes unchecked arguments to StdioServerParameters in backend/chainlit/server.py. Because npx supports the -c argument, an attacker can execute arbitrary shell commands with the privileges of the Chainlit process. If allowed_executables is unset, its None default is treated as allowing every executable. This issue is fixed in version 2.12.0.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Source: CVE Program / CVE List V5
Vulnerability Type
OS命令中使用的特殊元素转义处理不恰当(OS命令注入)
Source: CVE Program / CVE List V5
Vulnerability Title
Chainlit 命令注入漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Chainlit是chainlit组织开源的一个大模型对话界面框架。 Chainlit 2.4.0rc0版本至2.12.0之前版本存在命令注入漏洞，该漏洞源于MCP端点缺少身份验证且对用户控制的fullCommand参数验证不足，可能导致攻击者执行任意shell命令。
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
Chainlit chainlit >= 2.4.0rc0, < 2.12.0 -

II. Public POCs for CVE-2026-45018

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III. Intelligence Information for CVE-2026-45018

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Vendor Advisories for CVE-2026-45018 (2)

Vendor Pages for CVE-2026-45018 (1)

IV. Related Vulnerabilities

Same product: chainlit
Same vendor: Chainlit
Same weakness: CWE-78