CVE-2025-20393
Cisco Multiple Products Improper Input Validation Vulnerability
Cisco Multiple Products
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.
Exploitation status
CISA Known Exploited Vulnerabilities
Listed by CISA on 17 December 2025. US federal agencies were required to remediate it by 24 December 2025.
EPSS — exploitation probability
FIRST puts the probability of exploitation activity in the next 30 days at 32.4%, which is higher than 98.3% of all scored vulnerabilities. EPSS is a forecast of activity, not a measure of severity, and it is rescored daily.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H
Frequently asked questions
Is CVE-2025-20393 being exploited by ransomware groups?
No ransomware group in this database is currently recorded as exploiting CVE-2025-20393.
What does CVE-2025-20393 affect?
CVE-2025-20393 affects Cisco Multiple Products. 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.
How severe is CVE-2025-20393?
CVE-2025-20393 is rated CRITICAL with a CVSS base score of 10. EPSS puts the probability of exploitation in the next 30 days at 32.4%, higher than 98.3% of all scored vulnerabilities. It is listed in the CISA Known Exploited Vulnerabilities catalog, with a federal remediation deadline of 24 December 2025.
How should organisations respond to CVE-2025-20393?
Apply the vendor patch for Cisco Multiple Products as the first priority, and treat any internet-facing instance as the most urgent. Because this vulnerability is associated with ransomware activity, also review whether the affected systems were reachable before patching, rather than assuming that patching alone closes the incident.