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.
Juniper SIRT is not aware of any malicious exploitation of this vulnerability.
There are no direct workarounds for this issue.
One of the following mitigations will prevent malicious exploitation:
- Use access lists or firewall filters to limit access to the CLI only from trusted hosts and administrators.
- Utilize command authorization to limit the ability to enter config mode to trusted administrators.
The following software releases have been updated to resolve this specific issue:
Junos OS: 22.3R3-S5, 22.4R3-S10, 23.2R2-S7, 23.4R2-S8, 24.2R1, and all subsequent releases.
Junos OS Evolved: 23.2R2-S7-EVO, 23.4R2-S8-EVO, 24.2R1-EVO, and all subsequent releases.