Hackers Actively Exploiting Critical Zero-Day Flaw in 120+ Cisco Email Security Devices

Cisco warns of a critical zero-day vulnerability in email security devices, urging urgent defenses as attackers exploit the flaw.

By Content Team

Dec 21, 2025

ON THIS PAGE

Security researchers discovered at least 120 Cisco Secure Email Gateway and Web Manager devices vulnerable to CVE-2025-20393, a critical zero-day flaw that attackers are actively exploiting. No patch is currently available, leaving organizations exposed.

The vulnerable devices are part of over 650 Cisco email security appliances accessible online. These systems are crucial for filtering malicious emails and protecting networks from phishing and malware.

Cisco has released a security advisory urging immediate defensive measures and temporary mitigations until a permanent fix arrives. The company hasn't provided a timeline for the security update, making interim protections essential for affected organizations.

Source: Cyber Security News

Have questions about protecting your software?

Our escrow experts are standing by to help.

Book a free demo

Want more insights like this?