CVE-2026-21919
published 2026-04-09CVE-2026-21919: An Incorrect Synchronization vulnerability in the management daemon (mgd) of Juniper Networks Junos OS and Junos OS Evolved allows a network-based attacker…
PriorityP339medium6.5CVSS 3.1
AVNACLPRLUINSUCNINAH
EPSS
0.23%
13.6th percentile
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
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 ' from the CLI or with 'kill -9 ' 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;
Affected
13 ranges
| Vendor | Product | Version range | Fixed in |
|---|---|---|---|
| juniper | junos | — | — |
| juniper | junos | — | — |
| juniper | junos | — | — |
| juniper | junos_os | — | — |
| juniper | junos_os_evolved | — | — |
| juniper | junos_os_evolved | — | — |
| juniper | junos_os_evolved | — | — |
| juniper_networks | junos_os | >= 23.4 < 23.4R2-S4 | 23.4R2-S4 |
| juniper_networks | junos_os | >= 24.2 < 24.2R2-S1 | 24.2R2-S1 |
| juniper_networks | junos_os | >= 24.4 < 24.4R1-S3, 24.4R2 | 24.4R1-S3, 24.4R2 |
| juniper_networks | junos_os_evolved | >= 23.4 < 23.4R2-S5-EVO | 23.4R2-S5-EVO |
| juniper_networks | junos_os_evolved | >= 24.2 < 24.2R2-S1-EVO | 24.2R2-S1-EVO |
| juniper_networks | junos_os_evolved | >= 24.4 < 24.4R1-S3-EVO, 24.4R2-EVO | 24.4R1-S3-EVO, 24.4R2-EVO |
CVSS provenance
nvdv3.16.5MEDIUMCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
nvdv4.07.1HIGHCVSS: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
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VulDB
Juniper Junos OS/Junos OS Evolved Management Daemon incorrect synchronization (JSA106019)
vuldb·2026-04-10·CVSS 7.1
CVE-2026-21919 [HIGH] Juniper Junos OS/Junos OS Evolved Management Daemon incorrect synchronization (JSA106019)
A vulnerability identified as critical has been detected in Juniper Junos OS and Junos OS Evolved. Affected is an unknown function of the component Management Daemon. The manipulation leads to incorrect synchronization.
This vulnerability is traded as CVE-2026-21919. It is possible to initiate the attack remotely. There is no exploit available.
You should upgrade the affected component.
GHSA
GHSA-qv89-vxpv-h7vc: An Incorrect Synchronization vulnerability in the management daemon (mgd) of Juniper Networks Junos OS and Junos OS Evolved allows a network-based att
ghsa_unreviewed·2026-04-10
CVE-2026-21919 [HIGH] CWE-821 GHSA-qv89-vxpv-h7vc: An Incorrect Synchronization vulnerability in the management daemon (mgd) of Juniper Networks Junos OS and Junos OS Evolved allows a network-based att
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
root 20 0 501M 4640K lockf 1 0:01 0.00% mgd
If the system still
Juniper
CVE-2026-21919: An Incorrect Synchronization vulnerability in the management daemon (mgd) of Juniper Networks Junos OS and Junos OS Evolved allows a network-based att
vendor_juniper·2026-04-09·CVSS 6.5
CVE-2026-21919 [MEDIUM] CWE-821 CVE-2026-21919: An Incorrect Synchronization vulnerability in the management daemon (mgd) of Juniper Networks Junos OS and Junos OS Evolved allows a network-based att
CVE-2026-21919: 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
root 20 0 501M 4640K lockf 1 0:01 0.00% mgd
If t
No detection rules found.
No public exploits indexed.
No writeups or analysis indexed.
2026-04-09
Published