CVE-2025-20393: Cisco Multiple Products Improper Input Validation Vulnerability

Published Dec 17, 2025
·
Updated

A vulnerability in the Spam Quarantine feature of Cisco AsyncOS Software for Cisco Secure Email Gateway and Cisco Secure Email and Web Manager could allow an unauthenticated, remote attacker to execute arbitrary system commands on an affected device with root privileges. This vulnerability is due to insufficient validation of HTTP requests by the Spam Quarantine feature. An attacker could exploit this vulnerability by sending a crafted HTTP request to the affected device. A successful exploit could allow the attacker to execute arbitrary commands on the underlying operating system with root privileges.

Other sources

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

Affected Software

27 affected components
Cisco Multiple Products
All of the following
Any of the following
Cisco AsyncOS<15.0.5-016
Cisco AsyncOS>=15.5<15.5.4-012
Cisco AsyncOS>=16.0<16.0.4-016
Any of the following
Cisco Secure Email Gateway Virtual Appliance C100v
Cisco Secure Email Gateway Virtual Appliance C300v
Cisco Secure Email Gateway Virtual Appliance C600v
Cisco Secure Email Gateway C195
Cisco Secure Email Gateway C395
Cisco Secure Email Gateway C695
All of the following
Any of the following
Cisco AsyncOS<15.0.2-007
Cisco AsyncOS>=15.5<15.5.4-007
Cisco AsyncOS>=16.0<16.0.4-010
Any of the following
Cisco Secure Email And Web Manager Virtual Appliance M100v
Cisco Secure Email And Web Manager Virtual Appliance M300v
Cisco Secure Email And Web Manager Virtual Appliance M600v
Cisco Secure Email And Web Manager M170
Cisco Secure Email And Web Manager M190
Cisco Secure Email And Web Manager M195
Cisco Secure Email And Web Manager M380
Cisco Secure Email And Web Manager M390
Cisco Secure Email And Web Manager M390x
Cisco Secure Email And Web Manager M395
Cisco Secure Email And Web Manager M680
Cisco Secure Email And Web Manager M690
Cisco Secure Email And Web Manager M690x
Cisco Secure Email And Web Manager M695

Remediation

Recommended actions to resolve this vulnerability, in priority order.

  1. Remove

    Remove Cisco AsyncOS Software for Cisco Secure Email Gateway and Cisco Secure Email and Web Manager from your environment.

    Discontinue use of the product if mitigations are unavailable.

  2. Compensating control

    Apply mitigations per vendor instructions.

  3. Compensating control

    Follow applicable BOD 22-01 guidance for cloud services.

Event History

Dec 17, 2025
CVE Published
via CISA·12:00 AM
Known Exploited
via CISA·12:00 AM
Data Sourced
via CISA·12:00 AM
RemedyDescriptionAffected Software
CVE Published
via MITRE·04:47 PM
Data Sourced
via MITRE·04:47 PM
DescriptionSeverityWeakness
Data Sourced
via NVD·05:15 PM
DescriptionSeverityWeaknessAffected Software
News Published
via BleepingComputer·06:45 PM
News Published
via BleepingComputer·06:46 PM
News Published
via The Register·10:51 PM
News Published
via The Register·10:57 PM
Dec 18, 2025
News Published
via BleepingComputer·05:27 PM
Jan 8, 2026
News Published
via BleepingComputer·09:13 AM
Jan 15, 2026
News Published
via The Register·11:33 PM
Jan 16, 2026
News Published
via BleepingComputer·09:20 AM
Jan 22, 2026
News Published
via The Register·10:54 AM
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Frequently Asked Questions

1

What is the severity of CVE-2025-20393?

The severity of CVE-2025-20393 has not yet been disclosed, as Cisco is still investigating this potential vulnerability.

2

How do I fix CVE-2025-20393?

Currently, there is no official fix available for CVE-2025-20393 as Cisco is actively investigating the issue.

3

Why is CVE-2025-20393 a concern for Cisco users?

CVE-2025-20393 is a concern for Cisco users because it involves vulnerabilities in critical email and management appliances that could be exploited.

4

Which Cisco products are affected by CVE-2025-20393?

CVE-2025-20393 affects multiple Cisco products including the Cisco Secure Email Gateway and AsyncOS Software.

5

When will Cisco provide updates on CVE-2025-20393?

Cisco has stated they will update details regarding CVE-2025-20393 as more information becomes available during their investigation.

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