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CVE-2025-20393

Cisco Multiple Products Improper Input Validation

10.0 CRITICALActively exploited (CISA KEV)EPSS 32.4%
  1. Published17 Dec 2025
  2. Added to CISA KEV17 Dec 2025
  3. Remediation due24 Dec 2025
Actively exploited (CISA KEV)

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.

Added to KEV: 17 Dec 2025Federal remediation due: 24 Dec 2025

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 3.1 breakdown

Attack vectorNetwork
Attack complexityLow
Privileges requiredNone
User interactionNone
ScopeChanged
ConfidentialityHigh
IntegrityHigh
AvailabilityHigh
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H

Affected products

Cisco Asyncos≥ 15.5 < 15.5.4-007 · ≥ 15.5 < 15.5.4-012 · ≥ 16.0 < 16.0.4-010 · ≥ 16.0 < 16.0.4-016

Remediation

Fixed in
Cisco Asyncos≥ 15.5.4-007

References

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Frequently asked

Is CVE-2025-20393 being actively exploited?

Yes. CVE-2025-20393 is listed in the CISA Known Exploited Vulnerabilities (KEV) catalog, added 17 Dec 2025.

How severe is CVE-2025-20393?

CVE-2025-20393 has a CVSS 3.1 base score of 10.0, rated critical. EPSS estimates a 32.4% probability of exploitation.

Which products are affected by CVE-2025-20393?

Affected products include Cisco Asyncos.

How do I fix CVE-2025-20393?

Upgrade affected software to a fixed version, for example Cisco Asyncos 15.5.4-007 or later, then confirm no affected versions remain in your inventory.

How Secuno handles this

Secuno correlates vulnerabilities like CVE-2025-20393 against the real software inventory on every managed device, every day. Rather than a static severity, each match is scored in context: exploit availability, EPSS, the asset's exposure, and business criticality decide where it lands in the queue. Because it is on the CISA KEV list, Secuno flags any affected asset as top-priority automatically. If an affected version is present anywhere across your portfolio, it surfaces automatically with a prioritised remediation path.

See how prioritisation worksBook a demo

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Data from the NVD, CISA KEV catalog and FIRST EPSS. CVSS 3.1 base score shown where available.