An Incorrect Permission Assignment for Critical Resource vulnerability in the Juniper DHCP daemon (jdhcpd) of Juniper Networks Junos OS and Junos OS Evolved allows a local, low-privileged user to write to the Unix socket used to manage the jdhcpd process, resulting in complete control over the resource.

This vulnerability allows any low-privileged user logged into the system to connect to the Unix socket and issue commands to manage the DHCP service, in essence, taking administrative control of the local DHCP server or DHCP relay.

This issue affects:
Junos OS:

• all versions before 21.2R3-S10,
• all versions of 22.2,
• from 21.4 before 21.4R3-S12,
• from 22.4 before 22.4R3-S8,
• from 23.2 before 23.2R2-S5,
• from 23.4 before 23.4R2-S6,
• from 24.2 before 24.2R2-S2,
• from 24.4 before 24.4R2,
• from 25.2 before 25.2R1-S1, 25.2R2;

Junos OS Evolved:

• all versions before 22.4R3-S8-EVO,
• from 23.2 before 23.2R2-S5-EVO,
• from 23.4 before 23.4R2-S6-EVO,
• from 24.2 before 24.2R2-S2-EVO,
• from 24.4 before 24.4R2-EVO,
• from 25.2 before 25.2R1-S1-EVO, 25.2R2-EVO.

To be affected by this issue, a device must be configured with either:

[ forwarding-options dhcp-relay group <group-name> interface ... ]

or

[ system services dhcp-local-server group <group-name> interface ... ]

Juniper SIRT is not aware of any malicious exploitation of this vulnerability.

This issue was found during internal product security testing or research.

The following software releases have been updated to resolve this specific issue:

Junos OS: 21.2R3-S10, 22.4R3-S8, 23.2R2-S5, 23.4R2-S6, 24.2R2-S2, 24.4R2, 25.2R1-S1, 25.2R2, 25.4R1, and all subsequent releases.
Junos OS Evolved: 22.4R3-S8-EVO, 23.2R2-S5-EVO, 23.4R2-S6-EVO, 24.2R2-S2-EVO, 24.4R2-EVO, 25.2R1-S1-EVO, 25.2R2-EVO, 25.4R1-EVO, and all subsequent releases.

This issue is being tracked as 1877468 which is visible on the Customer Support website.

Note: Juniper SIRT's policy is not to evaluate releases which are beyond End of Engineering (EOE) or End of Life (EOL).

Manually change permissions of the Unix socket used to control the jdhcpd server to only allow root access. For example:

root@junos> file change-permission filename /mfs/var/run/jdhcpd_mgmt permission 4700

Note: This change will not be persistent across reboots.

2026-01-14: Initial Publication

• KB16613: Overview of the Juniper Networks SIRT Quarterly Security Bulletin Publication Process [juniper.net]
• KB16765: In which releases are vulnerabilities fixed? [juniper.net]
• KB16446: Common Vulnerability Scoring System (CVSS) and Juniper's Security Advisories [juniper.net]
• Report a Security Vulnerability - How to Contact the Juniper Networks Security Incident Response Team