⚠ Actively exploited
Added to CISA KEV on 2025-12-17. Federal agencies required to patch by 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..

CVE-2025-20393

Severity
10.0CRITICAL
EPSS
6.6%
top 8.82%
CISA KEV
KEV
Added 2025-12-17
Due 2025-12-24
Exploit
No known exploits
Timeline
PublishedDec 17
KEV addedDec 17
KEV dueDec 24
Latest updateJan 16
CISA 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.

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 c

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:HExploitability: 3.9 | Impact: 6.0

Affected Packages3 packages

CVEListV5cisco/cisco_secure_email18 versions+17
NVDcisco/asyncos15.515.5.4-012+5

🔴Vulnerability Details

3
CVEList
Cisco Secure Email Gateway and Cisco Secure Email and Web Manager Remote Command Execution Vulnerability2025-12-17
GHSA
GHSA-mrgj-cg36-fgq8: Cisco is aware of a potential vulnerability2025-12-17
VulnCheck
Cisco Multiple Products Improper Input Validation Vulnerability2025

📋Vendor Advisories

2
Cisco
Reports About Cyberattacks Against Cisco Secure Email Gateway And Cisco Secure Email and Web Manager2025-12-18
CISA
Cisco Multiple Products Improper Input Validation Vulnerability2025-12-17

🕵️Threat Intelligence

2
Bleepingcomputer
Cisco finally fixes AsyncOS zero-day exploited since November2026-01-16
Bleepingcomputer
Cisco warns of unpatched AsyncOS zero-day exploited in attacks2025-12-17
CVE-2025-20393 (CRITICAL CVSS 10) | A vulnerability in the Spam Quarant | cvebase.io