CVE-2025-20393
Published: December 17, 2025
Official Description
Cisco Secure Email Gateway, Secure Email, AsyncOS Software, and Web Manager appliances contains an improper input validation vulnerability that allows threat actors to execute arbitrary commands with root privileges on the underlying operating system of an affected appliance.
CISA KEV Advisory
Cisco Multiple Products Improper Input Validation Vulnerability
Cisco Secure Email Gateway, Secure Email, AsyncOS Software, and Web Manager appliances contains an improper input validation vulnerability that allows threat actors to execute arbitrary commands with root privileges on the underlying operating system of an affected appliance.
Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.
Risk Analysis
This critical vulnerability in Cisco Secure Email Gateway, Secure Email, AsyncOS Software, and Web Manager appliances allows threat actors to execute arbitrary commands with root privileges due to improper input validation. With a CVSS score of 10.0 and confirmed exploitation in the KEV catalog, this is an extremely urgent vulnerability.
This vulnerability is actively being exploited in the wild. The attack vector is network-based and does not require authentication or user interaction, making it remotely exploitable with low complexity.
Administrators must immediately apply the latest security updates for Cisco Secure Email Gateway, Secure Email, AsyncOS Software, and Web Manager appliances to prevent arbitrary command execution.
Technical Analysis
CVE-2025-20393 can be exploited remotely over the network without requiring physical or adjacent access, significantly expanding the attack surface for threat actors.
The vulnerability requires no privileges and no user interaction, making it a prime target for automated exploitation campaigns and worm-like propagation.
A successful exploit results in complete confidentiality breach (data exposure), full integrity compromise (data manipulation), availability disruption (denial of service), with a CVSS base score of 10.0.
The vulnerability has a "Changed" scope, meaning successful exploitation can impact components beyond the vulnerable component itself — such as the host operating system or adjacent services.
CISA has added CVE-2025-20393 to the Known Exploited Vulnerabilities (KEV) catalog, confirming active exploitation in the wild. U.S. federal agencies are required to patch this within the mandated timeframe, and all organizations should treat remediation as urgent.
CVSS v3.1 Vector Breakdown
Affected Vendors & Products
Exploit & PoC Resources
All References (1)
Quick Facts
Recommended Actions
- →Apply vendor patches immediately
- →Monitor CVE-2025-20393 in threat intel feeds
- →Review IDS/IPS signatures for exploitation attempts
- !CISA KEV: Federal agencies must patch per BOD 22-01 timeline
- !Active exploitation confirmed — treat as P1