CVE-2026-21919
Full vulnerability record from the local CVENow database.
Description
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. When 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. This issue can be monitored by checking for mgd processes in lockf state in the output of 'show system processes extensive': user@host> show system processes extensive | match mgd <pid> root 20 0 501M 4640K lockf 1 0:01 0.00% mgd If 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. This issue affects: Junos OS: * 23.4 versions before 23.4R2-S4, * 24.2 versions before 24.2R2-S1, * 24.4 versions before 24.4R1-S3, 24.4R2; This issue does not affect Junos OS versions before 23.4R1; Junos OS Evolved: * 23.4 versions before 23.4R2-S5-EVO, * 24.2 versions before 24.2R2-S1-EVO, * 24.4 versions before 24.4R1-S3-EVO, 24.4R2-EVO. This issue does not affect Junos OS Evolved versions before 23.4R1-EVO;
Severity
HIGH
CVSS score
7.1
(v4.0)
Vulnerability status
Analyzed
Source identifier
Published
2026-04-09 22:16:25.173000
Last modified
2026-10-26 21:10:00.170000
View original CVE JSON
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"sourceIdentifier": "[email protected]",
"published": "2026-04-09T22:16:25.173",
"lastModified": "2026-10-26T21:10:00.170",
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"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;"
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"value": "Una vulnerabilidad de sincronización incorrecta en el demonio de gestión (mgd) de Juniper Networks Junos OS y Junos OS Evolved permite a un atacante basado en red con privilegios bajos causar una denegación de servicio (DoS) completa del plano de gestión.\n\nCuando las sesiones NETCONF se establecen y desconectan rápidamente, un problema de bloqueo hace que los procesos mgd se cuelguen en un estado inutilizable. Cuando se ha alcanzado el número máximo de procesos mgd, no es posible iniciar nuevas sesiones. Esto lleva a la incapacidad de gestionar el dispositivo y requiere un ciclo de encendido para recuperarse.\n\nEste problema se puede monitorear buscando procesos mgd en estado lockf en la salida de ’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\nSi aún se puede acceder al sistema (ya sea a través de la CLI o como root, lo que aún podría ser posible como último recurso ya que esto no invocará mgd), los procesos mgd en este estado pueden terminarse con ’request system process terminate [PID]’ desde la CLI o con ’kill -9 [PID]’ desde la shell.\n\nEste problema afecta:\n\nJunos OS:\n\n * versiones 23.4 anteriores a 23.4R2-S4,\n * versiones 24.2 anteriores a 24.2R2-S1,\n * versiones 24.4 anteriores a 24.4R1-S3, 24.4R2;\n\nEste problema no afecta a las versiones de Junos OS anteriores a 23.4R1;\n\nJunos OS Evolved:\n\n * versiones 23.4 anteriores a 23.4R2-S5-EVO,\n * versiones 24.2 anteriores a 24.2R2-S1-EVO,\n * versiones 24.4 anteriores a 24.4R1-S3-EVO, 24.4R2-EVO.\n\nEste problema no afecta a las versiones de Junos OS Evolved anteriores a 23.4R1-EVO;"
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