CVE-2026-81315

Published: Ago 31, 2026 Last Modified: Ago 31, 2026

ExploitDB:

Other exploit source:

Google Dorks:

HIGH 7,4

Source: 6b3ad84c-e1a6-4bf7-a703-f496b71e49db

Attack Vector: network

Attack Complexity: low

Privileges Required: none

User Interaction: active

Confidentiality: N/A

Integrity: N/A

Availability: N/A

Description

AI Translation Available

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.