Cisco Secure Email Attacks: 0-Day Exploit Confirmed, No Fix Available

Forbes • December 18, 2025

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A critical cyberattack is underway, Cisco has confirmed, targeting Cisco Secure Email with a CVSS-rated 10/10 zero - day vulnerability.

The full story

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 (1)

Zero-day Exploit

Companies (1)

Platforms (1)

Cisco Secure Email