{
    "dataType": "CVE_RECORD",
    "dataVersion": "5.2",
    "cveMetadata": {
        "cveId": "CVE-2026-44429",
        "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
        "state": "PUBLISHED",
        "assignerShortName": "GitHub_M",
        "dateReserved": "2026-05-06T14:40:00.954Z",
        "datePublished": "2026-05-14T21:05:56.130Z",
        "dateUpdated": "2026-05-15T14:20:27.564Z"
    },
    "containers": {
        "cna": {
            "title": "MCP Registry: Stored XSS in catalogue UI via attribute-quote breakout in publisher-controlled `websiteUrl`",
            "problemTypes": [
                {
                    "descriptions": [
                        {
                            "cweId": "CWE-79",
                            "lang": "en",
                            "description": "CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')",
                            "type": "CWE"
                        }
                    ]
                },
                {
                    "descriptions": [
                        {
                            "cweId": "CWE-116",
                            "lang": "en",
                            "description": "CWE-116: Improper Encoding or Escaping of Output",
                            "type": "CWE"
                        }
                    ]
                }
            ],
            "metrics": [
                {
                    "cvssV4_0": {
                        "attackVector": "NETWORK",
                        "attackComplexity": "LOW",
                        "attackRequirements": "NONE",
                        "privilegesRequired": "LOW",
                        "userInteraction": "PASSIVE",
                        "vulnConfidentialityImpact": "NONE",
                        "vulnIntegrityImpact": "NONE",
                        "vulnAvailabilityImpact": "NONE",
                        "subConfidentialityImpact": "NONE",
                        "subIntegrityImpact": "LOW",
                        "subAvailabilityImpact": "LOW",
                        "baseScore": 5.1,
                        "baseSeverity": "MEDIUM",
                        "vectorString": "CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:P/VC:N/VI:N/VA:N/SC:N/SI:L/SA:L",
                        "version": "4.0"
                    }
                }
            ],
            "references": [
                {
                    "name": "https://github.com/modelcontextprotocol/registry/security/advisories/GHSA-rqv2-m695-f8j4",
                    "tags": [
                        "x_refsource_CONFIRM"
                    ],
                    "url": "https://github.com/modelcontextprotocol/registry/security/advisories/GHSA-rqv2-m695-f8j4"
                }
            ],
            "affected": [
                {
                    "vendor": "modelcontextprotocol",
                    "product": "registry",
                    "versions": [
                        {
                            "version": "< 1.7.7",
                            "status": "affected"
                        }
                    ]
                }
            ],
            "providerMetadata": {
                "orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
                "shortName": "GitHub_M",
                "dateUpdated": "2026-05-14T21:05:56.130Z"
            },
            "descriptions": [
                {
                    "lang": "en",
                    "value": "The MCP Registry provides MCP clients with a list of MCP servers, like an app store for MCP servers. Prior to 1.7.7, the public catalogue UI served at GET / (file internal/api/handlers/v0/ui_index.html) is vulnerable to stored cross-site scripting via the server.websiteUrl field of any published server.json. Server-side validation in internal/validators/validators.go (validateWebsiteURL) only checks that the URL parses, is absolute, and uses the https scheme; it does not reject quote characters. Client-side, the value is interpolated into a double-quoted href attribute via innerHTML, using a homegrown escapeHtml helper that performs the standard textContent → innerHTML round-trip. Per the HTML serialisation algorithm, that round-trip encodes only &, <, > and U+00A0 inside text nodes — it does not encode \" or '. A literal \" in websiteUrl therefore breaks out of the href attribute, allowing arbitrary on* event handlers to be appended to the same <a> element. The Content-Security-Policy on / is script-src 'self' 'unsafe-inline' https://cdn.tailwindcss.com, so the injected event handlers execute. Any user able to obtain a publish token (e.g. via POST /v0/auth/github-at with their own GitHub account, or POST /v0/auth/none on a deployment that has anonymous auth enabled) can plant a poisoned record visible to every visitor of the registry homepage. This vulnerability is fixed in 1.7.7."
                }
            ],
            "source": {
                "advisory": "GHSA-rqv2-m695-f8j4",
                "discovery": "UNKNOWN"
            }
        },
        "adp": [
            {
                "references": [
                    {
                        "url": "https://github.com/modelcontextprotocol/registry/security/advisories/GHSA-rqv2-m695-f8j4",
                        "tags": [
                            "exploit"
                        ]
                    }
                ],
                "metrics": [
                    {
                        "other": {
                            "type": "ssvc",
                            "content": {
                                "timestamp": "2026-05-15T14:19:51.887565Z",
                                "id": "CVE-2026-44429",
                                "options": [
                                    {
                                        "Exploitation": "poc"
                                    },
                                    {
                                        "Automatable": "no"
                                    },
                                    {
                                        "Technical Impact": "partial"
                                    }
                                ],
                                "role": "CISA Coordinator",
                                "version": "2.0.3"
                            }
                        }
                    }
                ],
                "title": "CISA ADP Vulnrichment",
                "providerMetadata": {
                    "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
                    "shortName": "CISA-ADP",
                    "dateUpdated": "2026-05-15T14:20:27.564Z"
                }
            }
        ]
    }
}