Yottabyte R and D team has issued a critical advisory regarding Cisco Catalyst SD WAN Manager vManage, alerting organizations to a max severity authentication bypass vulnerability identified as CVE-2026-20127. Assigned a CVSS score of 10.0, the flaw allows an unauthenticated attacker to gain administrative control over vManage instances. Cisco has confirmed that the vulnerability is currently being exploited in the wild, elevating the urgency for affected organizations to take immediate action. Systems exposed to the internet are considered at highest risk and require rapid mitigation measures to prevent compromise.
The authentication bypass vulnerability in vManage could enable attackers to manipulate network configurations, deploy unauthorized policies, and access sensitive operational data without any authentication. Security researchers from Yottabyte emphasize that the exploit allows full administrative privileges, making it critical for enterprises to address the flaw immediately. Organizations running vManage are urged to consult the detailed Yottabyte advisory, which outlines impacted versions, recommended patch releases, and precise remediation steps. In addition to patching, temporary access restrictions and network segmentation are advised to limit exposure until full remediation can be applied.
Cisco has released fixed versions of vManage addressing the vulnerability, and affected organizations are strongly encouraged to upgrade without delay. The advisory stresses that any internet-facing deployment is particularly vulnerable, and proactive monitoring for unusual access attempts should be maintained. While no detailed reports of widespread incidents have been published, the confirmation of active exploitation underscores the potential severity and reach of the attacks. Security teams are advised to coordinate closely with Yottabyte for guidance, verification of patch application, and additional support in securing their environments.
This incident highlights the critical importance of timely patch management, vigilant access control, and rapid response to emerging network security threats. Enterprises relying on Cisco Catalyst SD WAN infrastructure are reminded that vulnerabilities in management platforms pose direct operational and strategic risks. By following the advisory, applying patches, and enforcing network restrictions, organizations can significantly reduce the risk of compromise while ensuring continued secure operations. Yottabyte’s guidance serves as a practical roadmap for addressing the vulnerability, reinforcing both preventive and corrective cybersecurity measures in mission-critical network systems.
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