Junos OS and Junos OS Evolved: Configuration of a specific SSH option results in mgd crash

Summary

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.

Timeline

1. Jul 9, 2026, 9:01 PM UTCCVE published
2. Jul 10, 2026, 2:21 PM UTCCISA SSVC assessment

   Exploitation: poc · Automatable: no · Technical impact: partial

3. Jul 10, 2026, 2:21 PM UTCRecord last updated

Affected versions

• Juniper Networks Junos OS

  From 22.3 · fixed in 22.3R3-S5; From 22.4 · fixed in 22.4R3-S10; From 23.2 · fixed in 23.2R2-S7; From 23.4 · fixed in 23.4R2-S8

• Juniper Networks Junos OS Evolved

  From 23.2 · fixed in 23.2R2-S7-EVO; From 23.4 · fixed in 23.4R2-S8-EVO

References 2