GHSA-83X6-42HR-JC76

Vulnerability from github – Published: 2026-09-02 14:52 – Updated: 2026-09-02 14:52
VLAI
Summary
CKAN MCP Server: MQA server allowlist bypass via unanchored regex (`isValidMqaServer`)
Details

Summary

The ckan_get_mqa_quality and ckan_get_mqa_quality_details tools restrict their server_url argument to dati.gov.it via a regular expression. The regex is anchored only at the start and places no boundary after the host, so any URL whose host merely begins with dati.gov.it — or that uses dati.gov.it as URL userinfo before an @ — passes validation while actually targeting an attacker-controlled host.

Affected code

// src/tools/quality.ts
const ALLOWED_SERVER_PATTERNS = [
  /^https?:\/\/(www\.)?dati\.gov\.it/i        // <-- no end anchor / host boundary
];
export function isValidMqaServer(serverUrl: string): boolean {
  return ALLOWED_SERVER_PATTERNS.some(pattern => pattern.test(serverUrl));
}

All of the following return true:

URL Real host
https://dati.gov.it.attacker.com/x dati.gov.it.attacker.com (attacker)
http://dati.gov.it.evil.example/api dati.gov.it.evil.example (attacker)
https://dati.gov.it@attacker.com/x attacker.com (userinfo trick)

After passing this check, server_url flows into getMqaQuality/getMqaQualityDetails, which call makeCkanRequest(serverUrl, "package_show", { id }). The server therefore issues a request to the attacker-controlled host and returns its (parsed) response to the caller.

Impact

  • The intended "dati.gov.it only" trust boundary for the MQA tools is defeated; they can be driven against arbitrary external hosts.
  • The attacker host receives the request (including the dataset_id) and controls the response body that is surfaced back to the model/user — enabling response spoofing and, in an agentic setting, indirect prompt-injection content delivered under the guise of a trusted-portal tool.
  • Contributes to SSRF surface: while makeCkanRequest blocks private/internal IPs, this bypass removes the domain restriction that the code intends to enforce for these tools.

The @-userinfo variant is the most severe form because validation passes on a string whose actual host is fully attacker-chosen.

Proof of concept

poc/mqa-allowlist-poc.mjs runs the verbatim regex over benign and malicious URLs:

accepted  expected_legit  url
true      true            https://dati.gov.it/opendata          <- legit
true      false           https://dati.gov.it.attacker.com/x    <- BYPASS
true      false           http://dati.gov.it.evil.example/api   <- BYPASS
true      false           https://dati.gov.it@attacker.com/x    <- BYPASS

Remediation

Validate the parsed host, not the raw string. For example:

function isValidMqaServer(serverUrl) {
  let u; try { u = new URL(serverUrl); } catch { return false; }
  if (u.protocol !== "https:") return false;
  const h = u.hostname.toLowerCase();
  return h === "dati.gov.it" || h === "www.dati.gov.it";
  // or: h === "dati.gov.it" || h.endsWith(".dati.gov.it")
}

Anchoring the regex end-to-end (/^https:\/\/(www\.)?dati\.gov\.it(\/|$)/i) also closes the suffix trick, but URL-parsing + exact host comparison is the robust fix and also neutralizes the @-userinfo variant.

Severity
5.3 (Medium)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
Show details on source website
To clipboard 

{
  "affected": [
    {
      "package": {
        "ecosystem": "npm",
        "name": "@aborruso/ckan-mcp-server"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "0.4.112"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-73845"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-20",
      "CWE-625",
      "CWE-918"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-09-02T14:52:21Z",
    "nvd_published_at": "2026-08-14T17:20:36Z",
    "severity": "MODERATE"
  },
  "details": "## Summary\n\nThe `ckan_get_mqa_quality` and `ckan_get_mqa_quality_details` tools restrict their `server_url` argument to `dati.gov.it` via a regular expression. The regex is anchored only at the start and places no boundary after the host, so any URL whose host merely **begins with** `dati.gov.it` \u2014 or that uses `dati.gov.it` as URL *userinfo* before an `@` \u2014 passes validation while actually targeting an attacker-controlled host.\n\n## Affected code\n\n```js\n// src/tools/quality.ts\nconst ALLOWED_SERVER_PATTERNS = [\n  /^https?:\\/\\/(www\\.)?dati\\.gov\\.it/i        // \u003c-- no end anchor / host boundary\n];\nexport function isValidMqaServer(serverUrl: string): boolean {\n  return ALLOWED_SERVER_PATTERNS.some(pattern =\u003e pattern.test(serverUrl));\n}\n```\n\nAll of the following return `true`:\n\n| URL | Real host |\n|-----|-----------|\n| `https://dati.gov.it.attacker.com/x` | `dati.gov.it.attacker.com` (attacker) |\n| `http://dati.gov.it.evil.example/api` | `dati.gov.it.evil.example` (attacker) |\n| `https://dati.gov.it@attacker.com/x` | `attacker.com` (userinfo trick) |\n\nAfter passing this check, `server_url` flows into `getMqaQuality`/`getMqaQualityDetails`, which call `makeCkanRequest(serverUrl, \"package_show\", { id })`. The server therefore issues a request to the attacker-controlled host and returns its (parsed) response to the caller.\n\n## Impact\n\n- The intended \"dati.gov.it only\" trust boundary for the MQA tools is defeated; they can be driven against arbitrary external hosts.\n- The attacker host receives the request (including the `dataset_id`) and controls the response body that is surfaced back to the model/user \u2014 enabling response spoofing and, in an agentic setting, indirect prompt-injection content delivered under the guise of a trusted-portal tool.\n- Contributes to SSRF surface: while `makeCkanRequest` blocks private/internal IPs, this bypass removes the domain restriction that the code intends to enforce for these tools.\n\nThe `@`-userinfo variant is the most severe form because validation passes on a string whose *actual* host is fully attacker-chosen.\n\n## Proof of concept\n\n`poc/mqa-allowlist-poc.mjs` runs the verbatim regex over benign and malicious URLs:\n\n```\naccepted  expected_legit  url\ntrue      true            https://dati.gov.it/opendata          \u003c- legit\ntrue      false           https://dati.gov.it.attacker.com/x    \u003c- BYPASS\ntrue      false           http://dati.gov.it.evil.example/api   \u003c- BYPASS\ntrue      false           https://dati.gov.it@attacker.com/x    \u003c- BYPASS\n```\n\n## Remediation\n\nValidate the parsed host, not the raw string. For example:\n\n```js\nfunction isValidMqaServer(serverUrl) {\n  let u; try { u = new URL(serverUrl); } catch { return false; }\n  if (u.protocol !== \"https:\") return false;\n  const h = u.hostname.toLowerCase();\n  return h === \"dati.gov.it\" || h === \"www.dati.gov.it\";\n  // or: h === \"dati.gov.it\" || h.endsWith(\".dati.gov.it\")\n}\n```\n\nAnchoring the regex end-to-end (`/^https:\\/\\/(www\\.)?dati\\.gov\\.it(\\/|$)/i`) also closes the suffix trick, but URL-parsing + exact host comparison is the robust fix and also neutralizes the `@`-userinfo variant.",
  "id": "GHSA-83x6-42hr-jc76",
  "modified": "2026-09-02T14:52:21Z",
  "published": "2026-09-02T14:52:21Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/ondata/ckan-mcp-server/security/advisories/GHSA-83x6-42hr-jc76"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-73845"
    },
    {
      "type": "WEB",
      "url": "https://github.com/ondata/ckan-mcp-server/commit/8e1522f9bbfa1f3b21550f17887f60f133e24151"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/ondata/ckan-mcp-server"
    },
    {
      "type": "WEB",
      "url": "https://github.com/ondata/ckan-mcp-server/releases/tag/v0.4.112"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N",
      "type": "CVSS_V3"
    }
  ],
  "summary": "CKAN MCP Server: MQA server allowlist bypass via unanchored regex (`isValidMqaServer`)"
}



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