Race condition in Junos OS and Junos OS Evolved - CVE-2026-21919
Published: May 8, 2026
Vulnerability identifier: #VU130704
CSH Severity: Low
CVSS v4: 7.1 [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]
CVE-ID: CVE-2026-21919
CWE-ID: CWE-362
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote user to cause a denial of service.
The vulnerability exists due to incorrect synchronization in the management daemon (mgd) when handling rapid NETCONF session establishment and disconnection. A remote user can repeatedly connect and disconnect NETCONF sessions to cause a denial of service.
Only devices with NETCONF enabled are exposed. When the maximum number of mgd processes is reached, no new logins are possible, and recovery requires a power-cycle.
Affected software
Junos OS
Junos OS Evolved
Junos OS Evolved
How to mitigate CVE-2026-21919
Install security update from vendor's website.
Junos OS - addressed in versions 23.4R2-S4, 24.2R2-S1, 24.4R1-S3, 24.4R2, 25.2R1
Junos OS Evolved - addressed in versions 23.4R2-S5-EVO, 24.2R2-S1-EVO, 24.4R1-S3-EVO, 24.4R2-EVO, 25.2R1-EVO
Junos OS Evolved - addressed in versions 23.4R2-S5-EVO, 24.2R2-S1-EVO, 24.4R1-S3-EVO, 24.4R2-EVO, 25.2R1-EVO