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TI-2026-56145 Aliases CVE-2026-81315

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

Priority HIGH 68CWE-346Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
Active
Attack complexity
Low
Attack requirements
Present
Impact type
Security bypass
Confidentiality · integrity · availability
High · High · None
Fix status
Fixed

Attack profile from CVSS 4.0 · CNA. Fix status from CNA. Impact type from CWE-346.

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.

Why it matters now

Exploitation Proof of concept CISA SSVC · not in CISA KEV
EPSS 0.00278 20th percentileScored 2026-11-07
Fix Fixed ash_ai (ash-project): 1.0.0

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
Poc
Automatable
No
Technical impact
Total

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
ash-projectash_ai0.8.0 to before 1.0.01.0.0Patch availableCNA
  • ash_ai Vendorash-project Affected 0.8.0 to before 1.0.0 Fixed in 1.0.0 Patch available CNA

CPE names CNA · 1

CPEVersionsRoleVendor
cpe:2.3:a:ash-project:ash_ai:*:*:*:*:*:*:*:*———
  • cpe:2.3:a:ash-project:ash_ai:*:*:*:*:*:*:*:* Versions — — ·—

Remediation

  • Fix · CNA ash_ai (ash-project) Fixed in 1.0.0

Fixed in the same release

Records fixed by the same vendor advisory or release, as the CNA lists them.

  • Release ·

    ash-project ash_ai 1.0.0

    6 records Highest priority Priority HIGH 2 HIGH, 4 MEDIUM

    Other records, highest priority first

    • TI-2026-54252 EEx template evaluation of prompt content in AshAi enables remote code executionPriority HIGH 74
    • TI-2026-56918 Identity tool filter in AshAi accepts operator maps, allowing update or destroy of unidentified recordsPriority MEDIUM 64
    • TI-2026-53035 AshAi vectorize change leaks raw embedding-provider errors, including credentials, in a user-facing errorPriority MEDIUM 64
    Show all 6 records →

Timeline

  1. 2026-10-02 Threatist record created from CVE-2026-81315

References

Patch 1

Advisory 1

Other 2

  • TI-2026-56298 Query-complexity limit bypass via first/last pagination arguments in AshGraphql enables denial of service CVSS 4.0HIGH 8.7
  • TI-2026-52572 Unbounded atom creation from client-supplied RPC field names in AshTypescript field formatter CVSS 4.0HIGH 8.7
  • TI-2026-57010 Path traversal in AshAdmin file uploads via unsanitized client filename CVSS 4.0HIGH 8.3
  • TI-2026-26840 Ash Framework: Ash.Type.Module.cast_input/2 atom exhaustion via unchecked Module.concat allows BEAM VM crash CVSS 4.0HIGH 8.2
  • TI-2026-54252 EEx template evaluation of prompt content in AshAi enables remote code execution CVSS 4.0HIGH 8.9
  • TI-2026-54208 Stored XSS in AshAdmin relationship typeahead via unescaped label_field content CVSS 4.0HIGH 8.4
See all 90 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences