How severe is CVE-2025-20393?

CVE-2025-20393 has a CVSS score of 10/10, rated CRITICAL. Immediate patching is strongly recommended.

Which packages are affected by CVE-2025-20393?

Affected package information for CVE-2025-20393 is not yet fully mapped. Check the official advisory links for details.

How do I fix CVE-2025-20393?

No fixed version has been published for CVE-2025-20393 yet. Monitor the advisory for updates, apply mitigations recommended by the vendor, and use O3 Security to track when a fix becomes available in your stack.

Is CVE-2025-20393 actively exploited in the wild?

Yes. There are 1 known exploit references for CVE-2025-20393, including . All exploit code should only be run in an isolated sandbox environment for research or authorized testing — never against production systems without explicit written authorization.

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

CVE-2025-20393 has an EPSS (Exploit Prediction Scoring System) score of 6.5%, placing it in the 91th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

Is CVE-2025-20393 in the CISA Known Exploited Vulnerabilities catalog?

Yes. CVE-2025-20393 (Cisco Multiple Products Improper Input Validation Vulnerability) was added to CISA's Known Exploited Vulnerabilities (KEV) catalog on 2025-12-17. CISA required all US federal civilian agencies to remediate this vulnerability by 2025-12-24. The required action was: Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable. Being listed in the KEV catalog is the strongest possible confirmation of active exploitation — treat this as a critical priority.

What type of vulnerability is CVE-2025-20393?

CVE-2025-20393 is classified as Improper Input Validation (CWE-20). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

Which products and versions are affected by CVE-2025-20393?

CVE-2025-20393 affects cisco asyncos. Check the affected-products list on this page against your deployed version to confirm exposure.

When was CVE-2025-20393 published, and has it been updated?

CVE-2025-20393 was published on December 17, 2025 and was last updated on January 16, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

CISA KEV·Added 2025-12-17 — agencies required to remediate by 2025-12-24

CVE-2025-20393

CRITICAL

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…

Published

Dec 17, 2025

Updated

Jan 16, 2026

Affected

0 pkgs

Patched

None yet

Exploits

1 known

EPSS Exploitation Probability

via FIRST.org ↗

6.5%probability of exploitation in next 30 days

Lower Risk91th percentile0.00%

EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.

Description

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.

Affected Products

1 product · 6 configurations

asyncoscisco

≥ 16.0 && < 16.0.4-010

range

Exploits & PoCs

Research use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.

StasonJatham/cisco-sa-sma-attack-N9bf4

Script to detect CVE-2025-20393 for Cisco Secure Email Gateway And Cisco

⭐ 22🍴 1Jan 2026

Frequently Asked Questions

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&nbsp

O3 Security · Impact-Aware SCA

Is CVE-2025-20393 in your stack?

O3 detects CVE-2025-20393 across dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.

Scan my stack How O3 SCA works