CRITICAL ZERO-DAY – PATCH NOW CVE-2026-20127 (CVSS 10.0) in Cisco Catalyst SD ...

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This article is one source in a clustered incident — the cluster page carries the summary, timeline and every other outlet covering it.

Cisco SD-WAN Zero-Day Exploited by Threat Actor Since 2023 A cyber threat actor has been exploiting a zero-day vulnerability (CVE-2026-20127) in Cisco Catalyst SD-WAN Controller since 2023. This vulnerability allows unauthenticated remote attackers to bypass authentication and gain administrative privileges, potentially leading to long-term persistence in affected systems. Cisco and the Australian Cyber Security Centre have reported the ongoing exploitation of this vulnerability. 104 sources 82