Cisco SD-WAN Zero-Day Under Exploitation for 3 Years
The maximum-severity vulnerability CVE-2026-20127 was exploited by an unknown but sophisticated threat actor who left very little evidence behind.
Stay informed on Cisco security updates, threats, and solutions. Get the latest news and expert insights on Cisco information security developments.
Search across headline titles and summaries.
Background for this topic.
Cisco produces networking devices and software that manage data flow in enterprise and service provider networks, including routers, switches, and firewalls. These components are often central points controlling network traffic and access, making their integrity critical for secure communications and network stability.
Security risks with Cisco equipment commonly arise from firmware vulnerabilities, exposed management interfaces, and configuration errors that attackers can exploit to gain unauthorized access or disrupt services. Timely application of security patches and strict access controls on device management interfaces are essential to reduce exposure. Monitoring network devices for unusual activity also helps detect potential compromises early in environments relying on Cisco infrastructure.
The maximum-severity vulnerability CVE-2026-20127 was exploited by an unknown but sophisticated threat actor who left very little evidence behind.
A newly disclosed maximum-severity security flaw in Cisco Catalyst SD-WAN Controller (formerly vSmart) and Catalyst SD-WAN Manager (formerly vManage) has come under active exploitation in the wild as part of malicious activity that dates back to 2023
Cisco is warning that a critical authentication bypass vulnerability in Cisco Catalyst SD-WAN, tracked as CVE-2026-20127, was actively exploited in zero-day attacks that allowed remote attackers to compromise controllers and add malicious rogue peers to targeted networks. [...]