CVE-2026-20122 in Catalyst SD-WAN Manager
Summary
by MITRE • 02/25/2026
A vulnerability in the API of Cisco Catalyst SD-WAN Manager could allow an authenticated, remote attacker to overwrite arbitrary files on the local file system. To exploit this vulnerability, the attacker must have valid read-only credentials with API access on the affected system.
This vulnerability is due to improper file handling on the API interface of an affected system. An attacker could exploit this vulnerability by uploading a malicious file on the local file system. A successful exploit could allow the attacker to overwrite arbitrary files on the affected system and gain vmanage user privileges.
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Analysis
by VulDB Data Team • 04/21/2026
This vulnerability exists within the Cisco Catalyst SD-WAN Manager API interface, representing a critical file system manipulation flaw that enables authenticated remote attackers to execute arbitrary file overwrites. The vulnerability specifically affects systems where the API handles file operations without proper validation mechanisms, creating a pathway for malicious file uploads that can overwrite critical system files. The attack requires only read-only API credentials, making it particularly dangerous as it can be exploited by users with minimal privileges who have access to the application programming interface. This weakness directly violates the principle of least privilege and demonstrates inadequate input validation within the API's file handling components.
The technical exploitation mechanism relies on improper file handling within the API layer, where the system fails to properly validate or sanitize file upload operations before writing them to the local file system. Attackers can craft malicious file uploads that, when processed through the vulnerable API endpoint, result in arbitrary file overwrites. This flaw operates at the intersection of inadequate access controls and insufficient file validation, creating a path for privilege escalation through file system manipulation. The vulnerability's exploitation process typically involves uploading a crafted file that, upon processing, overwrites existing system files with malicious content, potentially allowing the attacker to gain elevated vmanage user privileges.
The operational impact of this vulnerability extends beyond simple file overwrites to encompass complete system compromise and privilege escalation. Successful exploitation can enable attackers to overwrite critical system files, configuration files, or even executable components, potentially leading to complete system takeover. The ability to gain vmanage user privileges represents a significant escalation from the initial read-only API access, as vmanage users typically have elevated system-level permissions. This vulnerability affects the integrity and availability of the entire SD-WAN management infrastructure, potentially disrupting network operations and creating persistent backdoors within the organization's network management systems.
Organizations should implement immediate mitigations including strict API access controls, enhanced file validation mechanisms, and comprehensive monitoring of file system operations. Network segmentation and privileged access management should be enforced to limit exposure of the vulnerable API endpoints. Regular security assessments and patch management processes must be prioritized to address this vulnerability. The flaw aligns with CWE-22 (Improper Limitation of a Pathname to a Restricted Directory) and CWE-73 (External Control of File Name or Path) categories, while also mapping to ATT&CK techniques involving privilege escalation and persistence through file system manipulation. Organizations should conduct thorough vulnerability assessments and ensure that all API endpoints properly validate file operations and implement proper access controls to prevent unauthorized file system modifications.