Critical Cisco SD-WAN bug exploited in zero-day attacks since 2023

The vulnerabilities, scored as critical, affect the company’s software-defined wide-area networking (SD-WAN) systems.

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.

Cisco has disclosed a critical zero-day vulnerability in its Catalyst SD-WAN products that threat actors have exploited since 2023 to bypass authentication and achieve root access. Tracked as CVE-2026-20127, the flaw affects core networking components and prompts urgent patching amid active attacks.sec.cloudapps. CVE-2026-20127 stems from a flaw in the peering authentication mechanism of Cisco Catalyst […] The post Critical Cisco SD-WAN 0-Day Vu…

Cybersecurity agencies across the Five Eyes alliance have issued an emergency directive warning that a critical Cisco SD-WAN vulnerability is being actively exploited to gain unauthorized access to federal networks. Officials confirmed that threat actors are targeting core SD-WAN control systems —infrastructure that manages traffic across government and enterprise networks — and urged organizations to patch affected devices immediately. Cisco’s …

Exploitation of a maximum severity authentication bypass zero-day vulnerability affecting Cisco Catalyst SD-WAN Controller and Manager has been reported. Immediate patching is recommended to thwart ongoing attacks.Key takeaways:CVE-2026-20127 is an Authentication Bypass Vulnerability affecting Cisco Catalyst SD-WAN Controller and Manager. Patches have been released and no workarounds are currently available. Exploitation in the wild has been obs…

The U.S. Cybersecurity and Infrastructure Security Agency (CISA) issued an emergency directive warning of a “cyber threat actor’s ongoing exploitation of Cisco SD-WAN systems,” describing the activity as presenting a significant risk to federal civilian executive branch networks.

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