CVE-2026-21919: Junos OS and Junos OS Evolved: A high frequency of connecting and disconnecting NETCONF sessions causes management unavailability
Juniper Networks · Junos OS
Vendor fix available · Affected: Juniper Networks Junos OS · Exploitation: unlikely (under 1%)
Not in CyberSIXT coverage yet: no article names this CVE. This page shows the public record.
Higher than 14% of scored CVEs
DescriptionCVE.org
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;
Affected products2
From the CVE record. A product or version that is not listed is unknown, not unaffected.
- Juniper Networks · Junos OSfrom 23.4 before 23.4R2-S4; from 24.2 before 24.2R2-S1; from 24.4 before 24.4R1-S3, 24.4R2
- Juniper Networks · Junos OS Evolvedfrom 23.4 before 23.4R2-S5-EVO; from 24.2 before 24.2R2-S1-EVO; from 24.4 before 24.4R1-S3-EVO, 24.4R2-EVO
On the Atlas
Every published CVE is on the CyberSIXT Atlas, grouped by weakness, vendor and month.
- Exploitation
- Unlikely (under 1%). EPSS under 1%, or no score yet.
- CISA KEV
- Not listed
- Public check
- No public nuclei template
- Vendor
- Juniper Networks
- Published
- April 2026
CoverageNo articles yet
No CyberSIXT article names CVE-2026-21919 yet, so there is no coverage timeline, action brief or change log for it. Everything on this page comes from the public CVE record, CISA KEV, EPSS and the nuclei template index. Search the archive or see the CVEs in the news.