Cisco customers encounter another SD-WAN zero

A flaw in the peering authentication mechanism of Cisco Catalyst SD-WAN Controller (formerly vSmart), Manager (formerly vManage), and Validator (formerly vBond) allows an unauthenticated, remote attacker to bypass authentication by sending crafted requests to an affected system. A successful exploit grants the attacker access as an internal, high-privileged, non-root user on the SD-WAN Controller, from which they can reach NETCONF and manipulate the network configuration of the entire SD-WAN fabric. Any organization operating these Cisco SD-WAN control-plane components is affected, and the critical CVSS 10.0 score reflects full network scope with no privileges or user interaction required. The flaw is confirmed exploited in the wild: CISA added it to the KEV on 2026-02-25, Cisco has confirmed active exploitation (including a compromise of a communications service provider), and Five Eyes allies have issued an active-exploitation warning, with EPSS at 88.2% (100th percentile).

Do: Upgrade affected Catalyst SD-WAN Controller, Manager, and Validator components per Cisco's PSIRT advisory (fixed versions are not specified in this data), and prioritize patching given confirmed in-the-wild exploitation. Follow CISA Emergency Directive 26-03 and the CISA Hunt & Hardening Guidance for Cisco SD-WAN Devices: hunt for compromise indicators such as unexpected high-privileged non-root logins and unauthorized NETCONF configuration changes, and restrict internet exposure of SD-WAN management interfaces. Where mitigations are unavailable, adhere to applicable BOD 22-01 cloud guidance or discontinue use of the product.

CVE-2026-20182 is a critical authentication flaw (CWE-287) in the control-connection peering authentication of Cisco Catalyst SD-WAN Controller (formerly vSmart), Manager (formerly vManage), and Validator (formerly vBond). Because the peering authentication mechanism does not work properly, an unauthenticated, remote attacker can send crafted requests during the control-connection handshake and log in to the controller as an internal, high-privileged, non-root user without valid credentials. With this access, the attacker can reach NETCONF and manipulate network configuration across the entire SD-WAN fabric. Any organization running these Catalyst SD-WAN control components is affected, and the flaw carries a CVSS 3.1 score of 10.0 and a 91.5% EPSS score. CISA added it to the Known Exploited Vulnerabilities catalog on 2026-05-14, confirming exploitation in the wild, amid a series of exploited Cisco SD-WAN zero-days including a compromise at a communications service provider.

Do: Upgrade affected Catalyst SD-WAN Controller, Manager, and Validator components to the fixed releases identified in Cisco's May 2026 advisory (version numbers are not provided in this data). Use the advisory's 'show control connections' guidance to inspect control-connection handshaking for anomalies and audit for unauthorized high-privileged non-root accounts and unexpected NETCONF sessions. Operators — especially federal agencies — should follow CISA Emergency Directive 26-03 and CISA's Hunt & Hardening Guidance for Cisco SD-WAN Devices, including restricting internet exposure of SD-WAN management interfaces until patched.

Cisco Catalyst SD-WAN Manager (formerly SD-WAN vManage) contains an improper encoding or escaping of output flaw (CWE-116) in its handling of user-supplied files. An attacker who already has authenticated access to the system can trigger it by supplying a crafted file, because the file's contents are not properly escaped before being processed. Successful exploitation yields arbitrary command execution with root privileges, giving the attacker full control of the SD-WAN management platform. Organizations running Cisco Catalyst SD-WAN Manager/vManage to manage their SD-WAN fabric are affected. The flaw was added to CISA's Known Exploited Vulnerabilities catalog on 2026-06-09, indicating active exploitation, though no public proof-of-concept is known and ransomware use has not been confirmed.

Do: Apply the fixed release per Cisco's security advisory (specific fixed versions are not included in the available data), and prioritize this patch given the KEV listing. Because the flaw requires authenticated local access, restrict management-plane access to trusted administrators and networks, review privileged accounts on the manager, and audit the system for unexpected processes or changes. Federal agencies must follow the KEV required action under BOD 22-01 (mitigate per vendor instructions or discontinue use).