CVE-2025-20393
Published 2025-12-17 · Updated 2026-06-17 · Source psirt@cisco.com
Summary
CVE-2025-20393 is a critical-severity (CVSS 10.0) vulnerability in Cisco Multiple Products. CISA added it to the Known Exploited Vulnerabilities catalog on December 17, 2025, which means exploitation in the wild has been confirmed; US federal agencies had to remediate it by December 24, 2025. CISA does not currently list it as used in ransomware campaigns. Cisco has 102 vulnerabilities in the KEV catalog, 7 of them linked to ransomware.
All 102 known-exploited Cisco vulnerabilities →Description
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.
CVSS vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H
CISA Known-Exploited Vulnerability
Product: Cisco — Multiple Products
Name: Cisco Multiple Products Improper Input Validation Vulnerability
Date added: 2025-12-17 · Due: 2025-12-24
Required action: Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.