Known exploited vulnerability
CVE-2025-20393
The short answer
CVE-2025-20393 affects Cisco Cisco Secure Email and is rated critical (CVSS 10.0). CISA added it to the Known Exploited Vulnerabilities catalog on 2025-12-17: attackers are using it, so patch it first.
What it is
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.
Weakness: CWE-20.
Severity
10.0 critical
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H
Exploited (CISA KEV)
Yes, since Dec 17, 2025
Federal due date Dec 24, 2025
EPSS, next 30 days
32%
Higher than 98% of scored CVEs
How it can be exploited
- Attack vector
- Network
- Attack complexity
- Low
- Privileges required
- None
- User interaction
- None
- Scope
- Changed
- Confidentiality impact
- High
- Integrity impact
- High
- Availability impact
- High
What CISA says to do
Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.
Affected products
Cisco Secure Email, Cisco Secure Email and Web Manager. NVD's record lists the exact affected versions.
References
Questions
Is CVE-2025-20393 being exploited?
Yes. CISA added CVE-2025-20393 to its Known Exploited Vulnerabilities catalog on 2025-12-17, with a federal remediation due date of 2025-12-24.
How do I fix CVE-2025-20393?
CISA's 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.
From NVD, CISA KEV, FIRST EPSS and OSV.dev, checked . Status on NVD: Analyzed. The description is NVD's text, quoted as published.
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