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
makeCkanRequestblocks 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)
{
"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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Experimental. This forecast is provided for visualization only and may change without notice. Do not use it for operational decisions.
Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.
Sightings
| Author | Source | Type | Date | Other |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or observed by the user.
- Confirmed: The vulnerability has been validated from an analyst's perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
- Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
- Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
- Not confirmed: The user expressed doubt about the validity of the vulnerability.
- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.
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The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the
vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base
model, served locally by ML-Gateway.
They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
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