Cisco Catalyst SD-WAN Manager Arbitrary File Creation and Overwrite Vulnerability (CVE-2026-20262) Advisory

1. Apply Official Security Patches

Refer to the Cisco Security Advisory (cisco-sa-sdwan-arbfw-c2rZvQ) and upgrade your SD-WAN Manager to the latest patched release.

2. Temporary Mitigations & Monitoring

If immediate patching is not feasible, implement the following mitigation strategies:

• Enforce Least Privilege: Restrict user privileges and closely monitor accounts with lower-privileged or single-task access.
• WAF/IPS Signature Deployment: Configure Web Application Firewalls or Intrusion Prevention Systems to detect path traversal sequences in file upload API requests.

  # Example Snort / Suricata Rule
  alert tcp any any -> any $HTTP_PORTS (msg:"COALITION Exploit Attempt - CVE-2026-20262 Path Traversal"; flow:established,to_server; content:"POST"; http_method; content:"/dataservice/"; http_uri; content:"../"; http_client_body; sid:1000001; rev:1;)

• Audit Logs: Regularly inspect SD-WAN Manager web UI and API access logs for anomalous file upload activities and directory traversal patterns.

This is a critical Path Traversal (CWE-22) and improper input validation vulnerability in the web UI of Cisco Catalyst SD-WAN Manager (formerly vManage).

The vulnerability exists because the affected software fails to properly validate user-supplied input during the file upload process. An authenticated attacker with at least low-privileged, single-task user credentials can exploit this by sending a crafted HTTP request to an affected API endpoint.

A successful exploit allows the attacker to write or overwrite arbitrary files on the underlying operating system. This capability can be leveraged to modify critical system configurations or inject malicious payloads, ultimately allowing the attacker to elevate privileges to root. Since this vulnerability is listed in the CISA KEV (Known Exploited Vulnerabilities) catalog, immediate remediation is highly recommended.