CVE-2025-59990 is a Cross-site Scripting (CWE-79) vulnerability affecting Juniper Networks Junos Space, a network management platform widely used for managing Juniper network devices. The vulnerability arises from improper neutralization of input during web page generation on the template creation pages. An attacker can inject malicious script tags into these pages, which are then executed in the context of any user who views the affected page. This includes users with administrative privileges, allowing the attacker to execute arbitrary commands with the victim’s permissions. The vulnerability does not require prior authentication but does require the victim to interact with the malicious content (user interaction). The CVSS v3.1 base score is 6.1 (medium severity), reflecting network attack vector, low attack complexity, no privileges required, but user interaction needed, and partial impact on confidentiality and integrity without affecting availability. The flaw affects all versions of Junos Space before 24.1R4, with no patches currently linked, and no known exploits reported in the wild as of the publication date. The vulnerability could be leveraged for session hijacking, credential theft, or unauthorized configuration changes, posing significant risks to network security and operational integrity.

For European organizations, this vulnerability poses a risk of unauthorized access and control over network management systems, potentially leading to exposure of sensitive network configurations and credentials. Successful exploitation could allow attackers to escalate privileges, manipulate network devices, or disrupt network operations indirectly by altering configurations. This is particularly critical for sectors relying heavily on Junos Space for managing critical infrastructure, such as telecommunications, finance, energy, and government networks. The compromise of administrative accounts could lead to lateral movement within networks, data breaches, and long-term persistence of threat actors. Although availability is not directly impacted, the integrity and confidentiality breaches could have cascading effects on network stability and trustworthiness of network management operations.

1. Apply the official Juniper Networks patch or upgrade to Junos Space version 24.1R4 or later as soon as it becomes available. 2. Until patches are applied, restrict access to the Junos Space management interface using network segmentation, VPNs, or IP whitelisting to limit exposure to trusted users only. 3. Implement strict input validation and sanitization on all user-supplied data in template creation pages to prevent script injection. 4. Deploy Content Security Policy (CSP) headers to restrict the execution of unauthorized scripts within the Junos Space web interface. 5. Educate users, especially administrators, to be cautious about interacting with untrusted links or templates within the management interface. 6. Monitor logs and network traffic for unusual activities or attempts to exploit XSS vulnerabilities. 7. Consider deploying Web Application Firewalls (WAF) with rules targeting XSS attack patterns on the management interface endpoints.