SEPTEMBER 19, 2026
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Case File

CVE-2026-21901

MEDIUM · CVSS 4.4 EPSS 0.12% Public Exploit

Source: NVD + CISA KEV + EPSS · Published 2026-07-09 · Last synced 2026-08-08

CyberRota Analysis

AI-Generated

A NULL Pointer Dereference vulnerability in the management daemon of Juniper Networks Junos OS and Junos OS Evolved allows local high-privileged users to exploit specific SSH configuration parameters, leading to a Denial of Service (DoS) condition through repeated crashes of the mgd process. Organizations using affected versions of Junos OS (22.3 prior to 22.3R3-S5, 22.4 prior to 22.4R3-S10, 23.2 prior to 23.2R2-S7, and 23.4 prior to 23.4R2-S8) and Junos OS Evolved (22.3R1-EVO prior to 23.2R2-S7-EVO and 23.4 prior to 23.4R2-S8-EVO) should prioritize remediation to prevent potential service disruptions.

Public Exploit Signal

A public exploit, PoC, GitHub repository or Metasploit reference was detected for this CVE.

Detected Signals
exploit
GitHub PoC Links

Note: these links are listed for security research and verification purposes only.

CVE
CVE-2026-21901
Severity
MEDIUM
CVSS
4.4
EPSS
0.12%

Original NVD Description

A NULL Pointer Dereference vulnerability in the management daemon (mgd) of Juniper Networks Junos OS and Junos OS Evolved allows a local, high-privileged attacker setting or deactivating a specific SSH configuration parameter to create a Denial of Service (DoS). A local high-privileged user configuring or deactivating a specific 'system services ssh' configuration parameter can exploit a null pointer dereference in one of the functions used by SSH. The function attempts to dereference a null pointer when accessing certain configuration data, resulting in an mgd process crash and restart. Continued execution of these configuration commands will create a sustained Denial of Service (DoS) condition. This issue affects: Junos OS: * from 22.3 before 22.3R3-S5; * from 22.4 before 22.4R3-S10; * from 23.2 before 23.2R2-S7; * from 23.4 before 23.4R2-S8. This issue does not affect Junos OS before 22.3R1. Junos OS Evolved: * from 22.3R1-EVO before 23.2R2-S7-EVO; * from 23.4 before 23.4R2-S8-EVO. This issue does not affect Junos OS Evolved before 22.3R1-EVO.