Overview
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.
Please adhere to Cisco's guidelines to assess exposure and mitigate risks. Check for signs of potential compromise on all internet accessible Cisco products affected by this vulnerability. Apply any final mitigations provided by the vendor as soon as they become available. For more information please see: https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-sma-attack-N9bf4 ; https://nvd.nist.gov/vuln/detail/CVE-2025-20393
Key Details
| Property | Value |
|---|---|
| CVE ID | CVE-2025-20393 |
| Vendor / Product | Cisco — Multiple Products |
| NVD Published | 2025-12-17 |
| NVD Last Modified | 2026-01-16 |
| CVSS 3.1 Score | 10 |
| CVSS 3.1 Vector | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H |
| Severity | CRITICAL |
| CWE | CWE-20 |
| CISA KEV Added | 2025-12-17 |
| CISA KEV Deadline | 2025-12-24 |
| Known Ransomware Use | No |
CVSS 3.1 Breakdown
Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Changed
Confidentiality
High
Integrity
High
Availability
High
Required Action
CISA BOD 22-01 Deadline: 2025-12-24.
Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.
Timeline
| Date | Event |
|---|---|
| 2025-12-17 | Added to CISA Known Exploited Vulnerabilities catalog |
| 2025-12-24 | CISA BOD 22-01 remediation deadline |
References
| Resource | Type |
|---|---|
| NVD — CVE-2025-20393 | Vulnerability Database |
| CISA KEV Catalog Entry | US Government |