Is CVE-2025-20393 in the CISA KEV catalog?

Yes. CVE-2025-20393 is on the CISA Known Exploited Vulnerabilities list, added 2025-12-17.

What is the CVSS severity of CVE-2025-20393?

CVE-2025-20393 has a CVSS v3 base score of 10.0 (CRITICAL).

What is the EPSS score for CVE-2025-20393?

CVE-2025-20393 has an EPSS score of 29.51% (98th percentile), estimating the probability of exploitation in the next 30 days.

How do I fix CVE-2025-20393?

Upgrade asyncos to 16.0.4-010 or later.

CVE & CISA-KEV Catalog

CVE-2025-20393

CRITICALCISA KEVEPSS 98th pctl

10.0

CVSS v3

NVD

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.

CWE-20Improper Input Validation

How to fix

Remediation Available

asyncosNVD

Affected:>= 16.0, < 16.0.4-010Fixed in:16.0.4-010CVE-2025-20393derived from NVD

TridentStack Control can deploy fixes like this automatically across your Windows, macOS, and Linux fleet. See how it works

Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.

CVSS v3 Vector

Exploitability

Attack VectorNetwork

Attack ComplexityLow

Privileges RequiredNone

User InteractionNone

ScopeChanged

Impact

ConfidentialityHigh

IntegrityHigh

AvailabilityHigh

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H

Exploit Intelligence

29.51%probability of exploitation in 30 days

98thpercentile

Very high risk: more likely to be exploited than 98% of all known CVEs.

Known Exploited Vulnerability (CISA KEV)

Cisco Multiple Products Improper Input Validation Vulnerability

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.

Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.

Remediation due: 2025-12-24

References

Vendor Advisory1

sec.cloudapps.cisco.com

Government Resource1

cisa.gov

Related Vulnerabilities

Other CWE-20 (Improper Input Validation) vulnerabilities, ordered by exploit likelihood. View all

CVE	Severity	CVSS	EPSS	Exploited	Fix
CVE-2024-3400	Critical	10.0	100%	KEV + Ransom	-
CVE-2021-45105	Medium	5.9	100%	-	Fix
CVE-2021-44228	Critical	10.0	100%	KEV + Ransom	Fix
CVE-2021-21985	Critical	9.8	100%	KEV + Ransom	Fix
CVE-2018-7600	Critical	9.8	100%	KEV + Ransom	Fix
CVE-2020-3452	High	7.5	100%	KEV	Fix

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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-01-16.