CVE-2025-59980 in Junos OS
Summary
by MITRE • 10/09/2025
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:
* all versions before 22.4R3-S8, * 23.2 versions before 23.2R2-S3, * 23.4 versions before 23.4R2.
Be aware that VulDB is the high quality source for vulnerability data.
Analysis
by VulDB Data Team • 10/25/2025
This vulnerability represents a critical authentication bypass flaw in Juniper Networks Junos OS FTP server implementation that undermines fundamental security controls. The issue stems from a primary weakness in the authentication mechanism where the system fails to properly validate credentials for specific user accounts. When the FTP server functionality is enabled and either an "ftp" or "anonymous" user account is configured, the system permits unauthorized access without requiring password validation. This misconfiguration creates a persistent security gap that allows network-based attackers to exploit the service and gain unauthorized access to system resources. The vulnerability specifically targets the authentication flow within the FTP service, where legitimate user accounts are not properly verified, leading to a complete bypass of the intended security controls. Such a flaw directly violates security principles by allowing unauthorized access to system resources that should remain protected through proper authentication mechanisms.
The technical implementation of this vulnerability demonstrates a classic case of insufficient authentication checks within the FTP server component of Junos OS. The system's failure to enforce password validation for designated user accounts creates a predictable attack vector that can be exploited without requiring any specialized tools or advanced techniques. The authentication bypass occurs at the service level where the system accepts connections from the "ftp" or "anonymous" accounts regardless of whether a valid password was provided. This weakness is particularly concerning because it affects core system functionality that is often enabled in production environments for legitimate administrative purposes. The vulnerability allows attackers to gain limited read-write access to files within the home directory of the compromised accounts, potentially enabling further exploitation or data exfiltration. This flaw is categorized under CWE-287, which addresses authentication bypass issues, and aligns with ATT&CK technique T1078.002 for Valid Accounts - Default Accounts, as it exploits pre-configured system accounts.
The operational impact of this vulnerability extends beyond simple unauthorized access to encompass potential system compromise and data exposure. Network-based attackers can leverage this weakness to access sensitive configuration files, logs, and other system data stored within the targeted user directories. The limited read-write access capability provides attackers with opportunities to modify system files, inject malicious content, or establish persistent access points within the network infrastructure. Organizations running affected Junos OS versions face significant risk of unauthorized system manipulation, particularly in environments where FTP services are enabled for legitimate administrative tasks. The vulnerability affects multiple version streams of Junos OS, indicating a widespread issue that requires immediate attention across various deployment scenarios. This authentication bypass creates an elevated risk for network security posture, as it allows attackers to operate within the system without detection, potentially leading to further compromise of network resources and infrastructure.
Mitigation strategies for this vulnerability require immediate implementation of security patches and configuration updates across all affected Junos OS deployments. Organizations should prioritize upgrading to the patched versions specified in the advisory, specifically versions 22.4R3-S8, 23.2R2-S3, and 23.4R2, to address the underlying authentication bypass mechanism. System administrators should disable FTP services on Junos devices when not required for legitimate business purposes, as this eliminates the attack surface entirely. Additionally, implementing network segmentation and access controls can help limit the impact of potential exploitation attempts. Security monitoring should be enhanced to detect unusual FTP login patterns and unauthorized access attempts. The remediation process should include reviewing and disabling any unnecessary user accounts, particularly the "ftp" and "anonymous" accounts that are commonly targeted by attackers. Regular security assessments and vulnerability scanning should be conducted to identify similar authentication bypass vulnerabilities in other network services and systems. Implementation of principle of least privilege should be enforced, ensuring that only authorized users have access to critical system resources and that default accounts are properly secured or disabled.