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CVE-2026-81315— MCP DNS-rebinding origin check in AshAi is bypassed by a spoofed X-Forwarded-Proto header

Quick assessment

Affected
ash-project ash_ai
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.

以下是该漏洞描述的中文翻译： Ash Project 的 ash_ai 中存在“源验证错误”漏洞 Ash Project 中的 存在源验证错误漏洞，允许恶意网页绕过 MCP 服务器的 DNS 重绑定（DNS-rebinding）防护机制，从而以用户的身份向用户的本地 MCP 服务器发起跨站点请求。 技术细节： 在 中，当 默认为 时， 函数在满足以下条件时会接受该源（origin）： 1. ； 2. 转发的协议（forwarded scheme）为 。 这两个值均可被攻击者控制： 来自 HTTP 头； 协议（sch

CVSS 7.4 · High
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I. Basic Information for CVE-2026-81315

Vulnerability Information
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Vulnerability Title
MCP DNS-rebinding origin check in AshAi is bypassed by a spoofed X-Forwarded-Proto header
Source: CVE Program / CVE List V5
Vulnerability Description
Origin Validation Error vulnerability in ash-project ash_ai allows a malicious web page to bypass the MCP server's DNS-rebinding protection and issue cross-site requests to a user's local MCP server with that user's actor. In AshAi.Mcp.Server, with the default allowed_origins: nil, origin_allowed?/3 accepts an origin when uri.host == conn.host and the forwarded scheme is https. Both values are attacker-controlled: conn.host comes from the Host header and the scheme is read from the raw x-forwarded-proto header with no trusted-proxy check. Under DNS rebinding the browser sends the attacker's origin and a matching host, and page JavaScript may set X-Forwarded-Proto: https, so the check passes with no TLS or proxy involved. The fix trusts only localhost origins by default; other origins require an explicit allowed_origins allowlist. This issue affects ash_ai: from 0.8.0 before 1.0.0.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:A/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N
Source: CVE Program / CVE List V5
Vulnerability Type
源验证错误
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
ash-project ash_ai 0.8.0 ~ 1.0.0 cpe:2.3:a:ash-project:ash_ai:*:*:*:*:*:*:*:*
ash-project ash_ai c94f0b17fbe252f68755ba512678586164ba6139 ~ 28af68d73134df0b8fb3aa6ab03e8fd795b07c21 cpe:2.3:a:ash-project:ash_ai:*:*:*:*:*:*:*:*

II. Public POCs for CVE-2026-81315

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III. Intelligence Information for CVE-2026-81315

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Other References for CVE-2026-81315 (4)

IV. Related Vulnerabilities

Same product: ash_ai
Same vendor: ash-project
Same weakness: CWE-346

V. Comments for CVE-2026-81315

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