EEF-CVE-2026-81315
- Source
- https://cna.erlef.org/osv/EEF-CVE-2026-81315.html
- Import Source
- https://cna.erlef.org/osv/EEF-CVE-2026-81315.json
- JSON Data
- https://api.osv.dev/v1/vulns/EEF-CVE-2026-81315
- Aliases
-
- CVE-2026-81315
- GHSA-c92r-f3rr-q49h
- Published
- 2026-08-31T00:57:55.910Z
- Modified
- 2026-08-31T01:10:34.697113186Z
- Severity
-
- 7.4 (High) CVSS_V4 - 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 CVSS Calculator
- Summary
- MCP DNS-rebinding origin check in AshAi is bypassed by a spoofed X-Forwarded-Proto header
- Details
-
Summary
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.
- Database specific
{ "cpe_ids": [ "cpe:2.3:a:ash-project:ash_ai:*:*:*:*:*:*:*:*" ], "capec_ids": [ "CAPEC-62" ], "cwe_ids": [ "CWE-346" ] }- References
- Credits
-
-
- Peter Ullrich - FINDER
-
- Peter Ullrich - REPORTER
-
- Zach Daniel / Ash Project - REMEDIATION_DEVELOPER
-
- Jonatan Männchen / EEF - COORDINATOR
-
Affected packages
Hex / ash_ai
Package
- Name
- ash_ai
- Purl
- pkg:hex/ash_ai