Cisco email security products actively targeted in zero-day campaign

Techradar • December 19, 2025

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Cisco confirms zero ‑ day (CVE‑2025‑20393) in Secure Email appliances exploited by China‑linked actors; Attackers deployed Aquashell backdoor, ...

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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 Email Security Products Targeted in Zero-Day Campaign by China-Linked Actors Cisco has confirmed a zero-day vulnerability (CVE-2025-20393) in its Secure Email appliances that is being exploited by actors linked to China. The attackers have deployed the Aquashell backdoor to establish persistence within affected systems. 6 sources 67

Extracted Entities

Attack Types (2)

Malware Zero-day Exploit

Companies (1)

Countries (1)

Malware (1)

Platforms (1)

Cisco Secure Email