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CVE-2025-20393

Cisco Multiple Products Improper Input Validation Vulnerability

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.

CRITICAL · CVSS 10 ⚠ CISA KEV EPSS 0.06476
Act now
  • Listed on CISA KEV (known exploited in the wild)
  • SSVC exploitation status: active
  • EPSS percentile: top 9% of all CVEs by exploitation likelihood
  • SSVC automatable: yes - attacks can be scripted at scale
  • CVSS base score ≥ 7.0
Sigma rules0 YARA rules0
⬢

Required Remediation

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

⬡

Weakness Classification

CWE-20Improper Input Validation
▤

Affected Products & Versions

6
cisco asyncos< 15.0.5-016
cisco asyncos>= 15.5 and < 15.5.4-012
cisco asyncos>= 16.0 and < 16.0.4-016
cisco asyncos< 15.0.2-007
cisco asyncos>= 15.5 and < 15.5.4-007
cisco asyncos>= 16.0 and < 16.0.4-010
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Scoring & Timeline

10
CRITICAL · CVSS v3.1 · psirt@cisco.com
View on NVD
Attack Vector
Network Adjacent Local Physical
Attack Complexity
Low High
Privileges Required
None Low High
User Interaction
None Required
Scope
Unchanged Changed
Confidentiality
None Low High
Integrity
None Low High
Availability
None Low High
Published to NVD17 Dec 2025 · 05:15 PM
CVSS VectorCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H
SSVC triage · cisa-vulnrichment
Exploitation
active
Automatable
yes
Technical impact
total
SSVC asks the questions that actually drive patch urgency: is it being exploited, can attacks be automated, and how total is the impact.
⚑

Vendor Advisories

2
cisaKEV-CVE-2025-20393
cisco-csafcisco-sa-sma-attack-N9bf4
🔗

References & Sources

2
Source URLs (vendor pages, mailing lists, write-ups). Exploit/PoC links are in their own section above to avoid duplication.
https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-sma-attack-N9bf4Vendor Advisory
https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2025-20393US Government Resource
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