Critical flaw in Catalyst SD-WAN enables passwordless access

Published on May 16, 2026 | Translated from Spanish

Cisco has confirmed that an authentication bypass vulnerability in its Catalyst SD-WAN controller is being actively exploited. This flaw allows unauthenticated remote attackers to bypass access controls and gain full administrative privileges over the system. The company recommends applying available security patches and reviewing configurations to reduce the risk of compromise.

cinematic technical illustration of a Cisco Catalyst SD-WAN controller motherboard mid-exploitation, glowing red alert indicators on the chassis, a digital padlock icon being shattered by a stylized lightning bolt, network cables disconnecting from ports, a shadowy figure silhouette reaching for a terminal screen showing a command line with admin privileges granted, dark server rack environment, red and cyan neon lighting, photorealistic hardware details, circuit traces visible on the board, dramatic shadows, ultra-detailed engineering visualization

Technical details of the authentication bypass 🔐

The vulnerability, identified as CVE-2024-XXXX, resides in the authentication mechanism of the SD-WAN controller. An attacker can send manipulated HTTP requests to bypass credential verification. This grants full access to the administration interface, allowing modification of traffic rules, data extraction, or deployment of malicious configurations. Cisco has published firmware updates for the affected versions. Administrators should prioritize installing these patches and segment the management network to limit exposure.

The open door nobody asked for 🚪

It seems Cisco decided to include an undocumented feature: VIP access for any visitor. No password, no username, not even a friendly smile is needed. Just a well-formed request and voilà, you're an administrator. It's like leaving the car keys in the ignition with the engine running in a rough neighborhood. Good thing attackers are kind enough to warn us by exploiting it.