Mandiant reveals how Cisco SD-WAN zero-day attacks gained root ...

What We Know

Mandiant has published technical findings showing that a previously unknown vulnerability in Cisco Catalyst SD‑WAN Manager (tracked as CVE‑2026‑20245) was exploited in the wild to gain root access to compromised appliances. Multiple reports describe an attack chain that delivered privileged access: attackers used an upload or input vector (reported in some writeups as a malicious CSV upload) and network-level techniques that researchers describe as "rogue peering" to reach SD‑WAN devices, obtain administrative privileges, and then escalate to root.

The exploitation occurred before public disclosure, with reporting that attackers were active at least weeks or months earlier; at least one communications service provider was confirmed as a victim where the attacker achieved the highest access level. The incident is being documented by vendors and cloud security teams (including a Google Cloud writeup) and sits amid a series of SD‑WAN zero‑days reported in 2026, prompting advisories and patching guidance from security stakeholders.