{"affected":[{"package":{"ecosystem":"Hex","name":"ash_ai","purl":"pkg:hex/ash_ai"},"ranges":[{"events":[{"introduced":"0.8.0"},{"fixed":"1.0.0"}],"type":"SEMVER"}],"versions":["0.8.0","0.8.1","0.8.2"]},{"ranges":[{"events":[{"introduced":"c94f0b17fbe252f68755ba512678586164ba6139"},{"fixed":"28af68d73134df0b8fb3aa6ab03e8fd795b07c21"}],"repo":"https://github.com/ash-project/ash_ai","type":"GIT"}]}],"aliases":["GHSA-c92r-f3rr-q49h","CVE-2026-81315"],"credits":[{"name":"Peter Ullrich","type":"FINDER"},{"name":"Peter Ullrich","type":"REPORTER"},{"name":"Zach Daniel / Ash Project","type":"REMEDIATION_DEVELOPER"},{"name":"Jonatan Männchen / EEF","type":"COORDINATOR"}],"database_specific":{"capec_ids":["CAPEC-62"],"cpe_ids":["cpe:2.3:a:ash-project:ash_ai:*:*:*:*:*:*:*:*"],"cwe_ids":["CWE-346"]},"details":"## Summary\n\nOrigin 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.\n\nIn 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.\n\nThis issue affects ash\\_ai: from 0.8.0 before 1.0.0.","id":"EEF-CVE-2026-81315","modified":"2026-08-31T00:57:56.380254Z","published":"2026-08-31T00:57:55.910Z","references":[{"type":"ADVISORY","url":"https://github.com/ash-project/ash_ai/security/advisories/GHSA-c92r-f3rr-q49h"},{"type":"WEB","url":"https://cna.erlef.org/cves/CVE-2026-81315.html"},{"type":"FIX","url":"https://github.com/ash-project/ash_ai/commit/28af68d73134df0b8fb3aa6ab03e8fd795b07c21"},{"type":"PACKAGE","url":"https://hex.pm/packages/ash_ai"}],"related":[],"schema_version":"1.7.3","severity":[{"score":"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","type":"CVSS_V4"}],"summary":"MCP DNS-rebinding origin check in AshAi is bypassed by a spoofed X-Forwarded-Proto header","upstream":[]}