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CVE-2026-120492— Chainlit 2.12.0 SSRF via Semicolon Path Segment in MCP allowed_urls

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 2.12.0 存在一个服务器端请求伪造（SSRF）漏洞。由于 函数未拒绝分号（ ）字符，未经身份验证的攻击者能够绕过针对路径范围的 MCP 条目。攻击者可以向 端点提交包含 片段的 MCP 网址，从而在那些会剥离分号路径参数的源站（origins）上，触发对超出操作者授权范围的路径的请求。

CVSS 5.4 · Medium

Affected Version Matrix 1

VendorProduct Version RangeStatus
Chainlit Chainlit 2.12.0 affected
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I. Basic Information for CVE-2026-120492

Vulnerability Information
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Vulnerability Title
Chainlit 2.12.0 SSRF via Semicolon Path Segment in MCP allowed_urls
Source: CVE Program / CVE List V5
Vulnerability Description
Chainlit 2.12.0 contains a server-side request forgery vulnerability that allows unauthenticated attackers to bypass path-scoped MCP allowed_urls entries because validate_mcp_url does not reject the semicolon character. Attackers can submit MCP URLs with '..;' segments to the /mcp endpoint, causing requests to paths outside the operator's grant on origins that strip semicolon path parameters.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:H/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 2.12.0 -

II. Public POCs for CVE-2026-120492

# POC Description Source Link Shenlong Link
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III. Intelligence Information for CVE-2026-120492

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Vendor Advisories for CVE-2026-120492 (1)

Other References for CVE-2026-120492 (3)

IV. Related Vulnerabilities

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