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CVE-2026-45019— Chainlit: SSRF via MCP SSE and streamable-http transports allows unauthenticated internal network access

Quick assessment

Affected
Chainlit chainlit
Exploitation
Public or AI PoC available; prioritize validation
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 之间，如果用户在 配置文件中将 设置为 ，则部署中的 POST /mcp 端点将在无需身份验证的情况下暴露。 对于 SSE（Server-Sent Events）和可流式传输 HTTP（streamable-http）传输方式， 中的 和 类型接受由用户控制的 URL 和可选的 HTTP 头字典，但未进行协议方案（scheme）验证、私有地址过滤或白名单检查。 中的 处理程序将这些未经验证的用

CVSS 7.2 · High EPSS 0.32% · P24

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-2026-45019

Vulnerability Information
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Vulnerability Title
Chainlit: SSRF via MCP SSE and streamable-http transports allows unauthenticated internal network access
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 sse and streamable-http transports, ConnectSseMCPRequest and ConnectStreamableHttpMCPRequest in backend/chainlit/types.py accept a user-controlled url and optional headers dictionary without scheme validation, private-address filtering, or an allowlist. The connect_mcp handler in backend/chainlit/server.py passes these values to sse_client() or streamablehttp_client(), allowing the Chainlit server to make blind outbound requests to arbitrary internal or external services, including cloud metadata endpoints, with attacker-controlled Authorization and Cookie headers. The SSE URL sink has existed since 2.4.0rc0, while attacker-controlled header forwarding and streamable-http support were added in 2.6.4. The response is consumed internally and not returned, but the attacker can issue state-changing authenticated requests, discover internal services, scan ports, and probe metadata endpoints. 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:C/C:L/I:L/A:N
Source: CVE Program / CVE List V5
Vulnerability Type
服务端请求伪造(SSRF)
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-2026-45019

# POC Description Source Link Shenlong Link
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Qwen3.6-35B-A3B · 11558 chars
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III. Intelligence Information for CVE-2026-45019

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Vendor Advisories for CVE-2026-45019 (2)

Vendor Pages for CVE-2026-45019 (1)

IV. Related Vulnerabilities

Same product: chainlit
Same vendor: Chainlit
Same weakness: CWE-918

V. Comments for CVE-2026-45019

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