CVSS: v3.1: 6.5 (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N) CVSS: v4.0: 6.9 (CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N/AU:Y/RE:M)
An Authentication Bypass by Primary Weakness in the FTP server of Juniper Networks Junos OS allows an unauthenticated, network-based attacker to get limited read-write access to files on the device.
When the FTP server is enabled and a user named "ftp" or "anonymous" is configured, that user can login without providing the configured password and then has read-write access to their home directory.
This issue affects Junos OS:
A system is only exploitable if ftp is enabled and a user with the name "ftp" or "anonymous" is configured:[ system services ftp ][ system login user (ftp | anonymous) ... ]
Juniper SIRT is not aware of any malicious exploitation of this vulnerability.
This issue was seen during production usage.
The following software releases have been updated to resolve this specific issue: 22.4R3-S8, 23.2R2-S3, 23.4R2, 24.2R1, and all subsequent releases.
This issue is being tracked as 1771132 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).
Choosing another name for the user "ftp" or "anonymous" will prevent exploitation of this issue.
2025-10-08: Initial Publication
2025-10-10: Updated the sentence describing the affected configuration to also mention anonymous