{
    "dataType": "CVE_RECORD",
    "dataVersion": "5.2",
    "cveMetadata": {
        "cveId": "CVE-2026-81315",
        "assignerOrgId": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
        "state": "PUBLISHED",
        "assignerShortName": "EEF",
        "dateReserved": "2026-08-30T20:00:01.860Z",
        "datePublished": "2026-08-31T00:57:55.910Z",
        "dateUpdated": "2026-08-31T00:57:55.910Z"
    },
    "containers": {
        "cna": {
            "affected": [
                {
                    "collectionURL": "https://repo.hex.pm",
                    "cpes": [
                        "cpe:2.3:a:ash-project:ash_ai:*:*:*:*:*:*:*:*"
                    ],
                    "defaultStatus": "unaffected",
                    "modules": [
                        "'Elixir.AshAi.Mcp.Server'"
                    ],
                    "packageName": "ash_ai",
                    "packageURL": "pkg:hex/ash_ai",
                    "product": "ash_ai",
                    "programFiles": [
                        "lib/ash_ai/mcp/server.ex"
                    ],
                    "programRoutines": [
                        {
                            "name": "'Elixir.AshAi.Mcp.Server':check_origin/2"
                        },
                        {
                            "name": "'Elixir.AshAi.Mcp.Server':origin_allowed?/3"
                        }
                    ],
                    "repo": "https://github.com/ash-project/ash_ai",
                    "vendor": "ash-project",
                    "versions": [
                        {
                            "lessThan": "1.0.0",
                            "status": "affected",
                            "version": "0.8.0",
                            "versionType": "semver"
                        }
                    ]
                },
                {
                    "collectionURL": "https://github.com",
                    "cpes": [
                        "cpe:2.3:a:ash-project:ash_ai:*:*:*:*:*:*:*:*"
                    ],
                    "defaultStatus": "unaffected",
                    "modules": [
                        "'Elixir.AshAi.Mcp.Server'"
                    ],
                    "packageName": "ash-project/ash_ai",
                    "packageURL": "pkg:github/ash-project/ash_ai",
                    "product": "ash_ai",
                    "programFiles": [
                        "lib/ash_ai/mcp/server.ex"
                    ],
                    "programRoutines": [
                        {
                            "name": "'Elixir.AshAi.Mcp.Server':check_origin/2"
                        },
                        {
                            "name": "'Elixir.AshAi.Mcp.Server':origin_allowed?/3"
                        }
                    ],
                    "repo": "https://github.com/ash-project/ash_ai",
                    "vendor": "ash-project",
                    "versions": [
                        {
                            "lessThan": "28af68d73134df0b8fb3aa6ab03e8fd795b07c21",
                            "status": "affected",
                            "version": "c94f0b17fbe252f68755ba512678586164ba6139",
                            "versionType": "git"
                        }
                    ]
                }
            ],
            "cpeApplicability": [
                {
                    "nodes": [
                        {
                            "cpeMatch": [
                                {
                                    "criteria": "cpe:2.3:a:ash-project:ash_ai:*:*:*:*:*:*:*:*",
                                    "versionEndExcluding": "1.0.0",
                                    "versionStartIncluding": "0.8.0",
                                    "vulnerable": true
                                }
                            ],
                            "negate": false,
                            "operator": "OR"
                        }
                    ],
                    "operator": "AND"
                }
            ],
            "credits": [
                {
                    "lang": "en",
                    "type": "finder",
                    "value": "Peter Ullrich"
                },
                {
                    "lang": "en",
                    "type": "reporter",
                    "value": "Peter Ullrich"
                },
                {
                    "lang": "en",
                    "type": "remediation developer",
                    "value": "Zach Daniel / Ash Project"
                },
                {
                    "lang": "en",
                    "type": "coordinator",
                    "value": "Jonatan Männchen / EEF"
                }
            ],
            "descriptions": [
                {
                    "lang": "en",
                    "supportingMedia": [
                        {
                            "base64": false,
                            "type": "text/html",
                            "value": "<p>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.</p>\n<p>In <code>AshAi.Mcp.Server</code>, with the default <code>allowed_origins: nil</code>, <code>origin_allowed?/3</code> accepts an origin when <code>uri.host == conn.host</code> and the forwarded scheme is <code>https</code>. Both values are attacker-controlled: <code>conn.host</code> comes from the <code>Host</code> header and the scheme is read from the raw <code>x-forwarded-proto</code> 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 <code>X-Forwarded-Proto: https</code>, so the check passes with no TLS or proxy involved. The fix trusts only localhost origins by default; other origins require an explicit <code>allowed_origins</code> allowlist.</p>\n<p>This issue affects ash_ai: from 0.8.0 before 1.0.0.</p>"
                        },
                        {
                            "base64": false,
                            "type": "text/markdown",
                            "value": "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.\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."
                        }
                    ],
                    "value": "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.\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."
                }
            ],
            "impacts": [
                {
                    "capecId": "CAPEC-62",
                    "descriptions": [
                        {
                            "lang": "en",
                            "value": "CAPEC-62 Cross Site Request Forgery"
                        }
                    ]
                }
            ],
            "metrics": [
                {
                    "cvssV4_0": {
                        "Automatable": "NOT_DEFINED",
                        "Recovery": "NOT_DEFINED",
                        "Safety": "NOT_DEFINED",
                        "attackComplexity": "LOW",
                        "attackRequirements": "PRESENT",
                        "attackVector": "NETWORK",
                        "baseScore": 7.4,
                        "baseSeverity": "HIGH",
                        "privilegesRequired": "NONE",
                        "providerUrgency": "NOT_DEFINED",
                        "subAvailabilityImpact": "NONE",
                        "subConfidentialityImpact": "NONE",
                        "subIntegrityImpact": "NONE",
                        "userInteraction": "ACTIVE",
                        "valueDensity": "NOT_DEFINED",
                        "vectorString": "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",
                        "version": "4.0",
                        "vulnAvailabilityImpact": "NONE",
                        "vulnConfidentialityImpact": "HIGH",
                        "vulnIntegrityImpact": "HIGH",
                        "vulnerabilityResponseEffort": "NOT_DEFINED"
                    },
                    "format": "CVSS",
                    "scenarios": [
                        {
                            "lang": "en",
                            "value": "GENERAL"
                        }
                    ]
                }
            ],
            "problemTypes": [
                {
                    "descriptions": [
                        {
                            "cweId": "CWE-346",
                            "description": "CWE-346 Origin Validation Error",
                            "lang": "en",
                            "type": "CWE"
                        }
                    ]
                }
            ],
            "providerMetadata": {
                "orgId": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
                "shortName": "EEF",
                "dateUpdated": "2026-08-31T00:57:55.910Z"
            },
            "references": [
                {
                    "tags": [
                        "vendor-advisory",
                        "related"
                    ],
                    "url": "https://github.com/ash-project/ash_ai/security/advisories/GHSA-c92r-f3rr-q49h"
                },
                {
                    "tags": [
                        "related"
                    ],
                    "url": "https://cna.erlef.org/cves/CVE-2026-81315.html"
                },
                {
                    "tags": [
                        "related"
                    ],
                    "url": "https://osv.dev/vulnerability/EEF-CVE-2026-81315"
                },
                {
                    "tags": [
                        "patch"
                    ],
                    "url": "https://github.com/ash-project/ash_ai/commit/28af68d73134df0b8fb3aa6ab03e8fd795b07c21"
                }
            ],
            "source": {
                "discovery": "EXTERNAL"
            },
            "title": "MCP DNS-rebinding origin check in AshAi is bypassed by a spoofed X-Forwarded-Proto header"
        }
    }
}