CVE-2025-20187 is a medium-severity vulnerability affecting Cisco Catalyst SD-WAN Manager (formerly Cisco SD-WAN vManage). The flaw exists in the application data endpoints of the product, where improper validation of API requests allows an authenticated remote attacker to perform directory traversal attacks. By exploiting this vulnerability, an attacker can write arbitrary files to any location on the affected system. This is achieved by sending specially crafted malicious requests to the vulnerable APIs, bypassing the intended pathname restrictions that should limit file operations to a restricted directory. The vulnerability requires the attacker to have valid authentication credentials, but no user interaction is needed beyond that. The CVSS v3.1 base score is 6.5, reflecting a network attack vector with low attack complexity, requiring privileges but no user interaction, and impacting integrity without affecting confidentiality or availability. The affected versions span a broad range of Cisco Catalyst SD-WAN Manager releases, including many versions from 17.2.x through 20.15.1, indicating a long-standing issue across multiple product iterations. No known exploits are currently reported in the wild, and no patches or mitigation links are provided in the source data, suggesting organizations should proactively monitor Cisco advisories for updates. The vulnerability could allow attackers to implant malicious files, potentially leading to further compromise such as privilege escalation, persistent backdoors, or disruption of SD-WAN management operations.

For European organizations, the impact of this vulnerability could be significant, especially for enterprises and service providers relying on Cisco Catalyst SD-WAN Manager for network orchestration and management. Successful exploitation could allow attackers to write arbitrary files, potentially enabling them to deploy malicious scripts, modify configurations, or implant backdoors within the SD-WAN management infrastructure. This could lead to integrity breaches of network management data, unauthorized changes to network policies, or lateral movement within the corporate network. Given the critical role of SD-WAN in ensuring secure and reliable connectivity across distributed sites, such compromises could disrupt business operations, degrade network performance, or expose sensitive internal communications. The requirement for authentication limits exposure to insider threats or attackers who have already compromised credentials, but the broad version range affected increases the risk for organizations that have not maintained up-to-date software. Additionally, the lack of confidentiality impact reduces the risk of direct data leakage, but the integrity impact alone can have cascading effects on network security and availability indirectly.

European organizations should take immediate steps to mitigate this vulnerability beyond generic patching advice. First, conduct an inventory of all Cisco Catalyst SD-WAN Manager instances and verify their software versions against the affected list. Prioritize upgrading to the latest Cisco-recommended patched versions as soon as they become available. Until patches are applied, restrict access to the SD-WAN Manager interfaces to trusted administrative networks and enforce strong multi-factor authentication to reduce the risk of credential compromise. Implement strict API request validation and monitoring to detect anomalous or suspicious directory traversal patterns. Employ network segmentation to isolate SD-WAN management systems from general user networks and limit lateral movement possibilities. Regularly audit file system integrity on SD-WAN Manager servers to detect unauthorized file writes. Finally, maintain vigilant logging and alerting on administrative actions and API calls to quickly identify potential exploitation attempts.