CVE-2025-59957: Junos OS: EX4600 Series and QFX5000 Series: An attacker with physical access can open a persistent backdoor
An Origin Validation Error vulnerability in an insufficient protected file of Juniper Networks Junos OS on EX4600 Series and QFX5000 Series allows an unauthenticated attacker with physical access to the device to create a backdoor which allows complete control of the system.
When a device isn't configured with a root password, an attacker can modify a specific file. It's contents will be added to the Junos configuration of the device without being visible. This allows for the addition of any configuration unknown
to the actual operator, which includes users, IP addresses and other configuration which could allow unauthorized access to the device. This exploit is persistent across reboots and even zeroization.
The indicator of compromise is a modified /etc/config/<platform>-defaults[-flex].conf file. Review that file for unexpected configuration statements, or compare it to an unmodified version which can be extracted from the original Juniper software image file. For details on the extraction procedure please contact Juniper Technical Assistance Center (JTAC).
To restore the device to a trusted initial configuration the system needs to be reinstalled from physical media.
This issue affects Junos OS on EX4600 Series and QFX5000 Series:
All versions before 21.4R3, 22.2 versions before 22.2R3-S3.
Affected Software
Remediation
Information
Event History
Frequently Asked Questions
What is the severity of CVE-2025-59957?
CVE-2025-59957 is considered a high severity vulnerability due to the potential for an unauthenticated attacker with physical access to compromise the system.
How do I fix CVE-2025-59957?
To fix CVE-2025-59957, ensure that physical security measures are in place to prevent unauthorized access to the Juniper Networks devices.
What systems are affected by CVE-2025-59957?
CVE-2025-59957 affects Juniper Networks Junos OS on EX4600 Series and QFX5000 Series hardware.
What can an attacker do if they exploit CVE-2025-59957?
If exploited, an attacker can create a backdoor that provides complete control over the affected Junos OS device.
How can I mitigate the risk of CVE-2025-59957?
Mitigation of CVE-2025-59957 includes implementing strict physical security protocols and monitoring access to the Juniper Networking equipment.