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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 是一个用于构建生产级对话式 AI 应用的 Python 框架。在版本 2.4.0rc0 至 2.12.0 期间，若在 配置文件中将 设置为 ，则 Chainlit 部署中的 端点将在无需身份验证的情况下公开暴露。 对于 stdio 传输方式，该端点接受用户可控的 字符串。后端代码 中的 函数仅对可执行文件名称进行检查，并对照配置项 进行验证，而未经验证的用户参数仍会被传递给 中的 。由于 支持 参数，攻击者可以利用此漏洞以 Chainlit 进程的权限执行任意 shell 命令。 此外，如果 未设

CVSS 9.8 · Critical EPSS 0.65% · P49

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

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

V. Comments for CVE-2026-45018

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