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Known Exploited Vulnerability
10.0
CRITICAL CVSS 3.1
CVE-2025-20393
Cisco Multiple Products Improper Input Validation Vulnerability - [Actively Exploited]
Description

Cisco is aware of a potential vulnerability.  Cisco is currently investigating and will update these details as appropriate as more information becomes available.

INFO

Published Date :

Dec. 17, 2025, 5:15 p.m.

Last Modified :

Dec. 18, 2025, 3:41 p.m.

Remotely Exploit :

Yes !

Source :

[email protected]
CISA Notification
CISA KEV (Known Exploited Vulnerabilities)

For the benefit of the cybersecurity community and network defenders—and to help every organization better manage vulnerabilities and keep pace with threat activity—CISA maintains the authoritative source of vulnerabilities that have been exploited in the wild.

Description :

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.

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.

Notes :

Please adhere to Cisco's guidelines to assess exposure and mitigate risks. Apply any final mitigations provided by the vendor as soon as they become available. For more information please see: https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-sma-attack-N9bf4 ; https://nvd.nist.gov/vuln/detail/CVE-2025-20393

Affected Products

The following products are affected by CVE-2025-20393 vulnerability. Even if cvefeed.io is aware of the exact versions of the products that are affected, the information is not represented in the table below.

ID Vendor Product Action
1 Cisco secure_email_and_web_manager
2 Cisco asyncos
3 Cisco secure_email_gateway
4 Cisco secure_email_gateway_virtual_appliance_c100v
5 Cisco secure_email_gateway_virtual_appliance_c300v
6 Cisco secure_email_gateway_virtual_appliance_c600v
7 Cisco secure_email_gateway_c195
8 Cisco secure_email_gateway_c395
9 Cisco secure_email_gateway_c695
10 Cisco secure_email_and_web_manager_virtual_appliance_m100v
11 Cisco secure_email_and_web_manager_virtual_appliance_m300v
12 Cisco secure_email_and_web_manager_virtual_appliance_m600v
13 Cisco secure_email_and_web_manager_m170
14 Cisco secure_email_and_web_manager_m190
15 Cisco secure_email_and_web_manager_m195
16 Cisco secure_email_and_web_manager_m380
17 Cisco secure_email_and_web_manager_m390
18 Cisco secure_email_and_web_manager_m390x
19 Cisco secure_email_and_web_manager_m395
20 Cisco secure_email_and_web_manager_m680
21 Cisco secure_email_and_web_manager_m690
22 Cisco secure_email_and_web_manager_m690x
23 Cisco secure_email_and_web_manager_m695
: Total Affected Vendor : 1 | Products : 23
CVSS Scores
The Common Vulnerability Scoring System is a standardized framework for assessing the severity of vulnerabilities in software and systems. We collect and displays CVSS scores from various sources for each CVE.
Score Version Severity Vector Exploitability Score Impact Score Source
CVSS 3.1 CRITICAL [email protected]
Solution
Stay updated on Cisco's investigation and apply patches when released.
  • Monitor Cisco for vulnerability updates.
  • Apply security patches when available.
Public PoC/Exploit Available at Github

CVE-2025-20393 has a 5 public PoC/Exploit available at Github. Go to the Public Exploits tab to see the list.

References to Advisories, Solutions, and Tools

Here, you will find a curated list of external links that provide in-depth information, practical solutions, and valuable tools related to CVE-2025-20393.

URL Resource
https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-sma-attack-N9bf4 Vendor Advisory
https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2025-20393 US Government Resource
CWE - Common Weakness Enumeration

While CVE identifies specific instances of vulnerabilities, CWE categorizes the common flaws or weaknesses that can lead to vulnerabilities. CVE-2025-20393 is associated with the following CWEs:

Common Attack Pattern Enumeration and Classification (CAPEC)

Common Attack Pattern Enumeration and Classification (CAPEC) stores attack patterns, which are descriptions of the common attributes and approaches employed by adversaries to exploit the CVE-2025-20393 weaknesses.

CAPEC-3: Using Leading 'Ghost' Character Sequences to Bypass Input Filters Using Leading 'Ghost' Character Sequences to Bypass Input Filters CAPEC-7: Blind SQL Injection Blind SQL Injection CAPEC-8: Buffer Overflow in an API Call Buffer Overflow in an API Call CAPEC-9: Buffer Overflow in Local Command-Line Utilities Buffer Overflow in Local Command-Line Utilities CAPEC-10: Buffer Overflow via Environment Variables Buffer Overflow via Environment Variables CAPEC-13: Subverting Environment Variable Values Subverting Environment Variable Values CAPEC-14: Client-side Injection-induced Buffer Overflow Client-side Injection-induced Buffer Overflow CAPEC-22: Exploiting Trust in Client Exploiting Trust in Client CAPEC-23: File Content Injection File Content Injection CAPEC-24: Filter Failure through Buffer Overflow Filter Failure through Buffer Overflow CAPEC-28: Fuzzing Fuzzing CAPEC-31: Accessing/Intercepting/Modifying HTTP Cookies Accessing/Intercepting/Modifying HTTP Cookies CAPEC-42: MIME Conversion MIME Conversion CAPEC-43: Exploiting Multiple Input Interpretation Layers Exploiting Multiple Input Interpretation Layers CAPEC-45: Buffer Overflow via Symbolic Links Buffer Overflow via Symbolic Links CAPEC-46: Overflow Variables and Tags Overflow Variables and Tags CAPEC-47: Buffer Overflow via Parameter Expansion Buffer Overflow via Parameter Expansion CAPEC-52: Embedding NULL Bytes Embedding NULL Bytes CAPEC-53: Postfix, Null Terminate, and Backslash Postfix, Null Terminate, and Backslash CAPEC-63: Cross-Site Scripting (XSS) Cross-Site Scripting (XSS) CAPEC-64: Using Slashes and URL Encoding Combined to Bypass Validation Logic Using Slashes and URL Encoding Combined to Bypass Validation Logic CAPEC-67: String Format Overflow in syslog() String Format Overflow in syslog() CAPEC-71: Using Unicode Encoding to Bypass Validation Logic Using Unicode Encoding to Bypass Validation Logic CAPEC-72: URL Encoding URL Encoding CAPEC-73: User-Controlled Filename User-Controlled Filename CAPEC-78: Using Escaped Slashes in Alternate Encoding Using Escaped Slashes in Alternate Encoding CAPEC-79: Using Slashes in Alternate Encoding Using Slashes in Alternate Encoding CAPEC-80: Using UTF-8 Encoding to Bypass Validation Logic Using UTF-8 Encoding to Bypass Validation Logic CAPEC-81: Web Server Logs Tampering Web Server Logs Tampering CAPEC-83: XPath Injection XPath Injection CAPEC-85: AJAX Footprinting AJAX Footprinting CAPEC-88: OS Command Injection OS Command Injection CAPEC-101: Server Side Include (SSI) Injection Server Side Include (SSI) Injection CAPEC-104: Cross Zone Scripting Cross Zone Scripting CAPEC-108: Command Line Execution through SQL Injection Command Line Execution through SQL Injection CAPEC-109: Object Relational Mapping Injection Object Relational Mapping Injection CAPEC-110: SQL Injection through SOAP Parameter Tampering SQL Injection through SOAP Parameter Tampering CAPEC-120: Double Encoding Double Encoding CAPEC-135: Format String Injection Format String Injection CAPEC-136: LDAP Injection LDAP Injection CAPEC-153: Input Data Manipulation Input Data Manipulation CAPEC-182: Flash Injection Flash Injection CAPEC-209: XSS Using MIME Type Mismatch XSS Using MIME Type Mismatch CAPEC-230: Serialized Data with Nested Payloads Serialized Data with Nested Payloads CAPEC-231: Oversized Serialized Data Payloads Oversized Serialized Data Payloads CAPEC-250: XML Injection XML Injection CAPEC-261: Fuzzing for garnering other adjacent user/sensitive data Fuzzing for garnering other adjacent user/sensitive data CAPEC-267: Leverage Alternate Encoding Leverage Alternate Encoding CAPEC-473: Signature Spoof Signature Spoof CAPEC-588: DOM-Based XSS DOM-Based XSS CAPEC-664: Server Side Request Forgery Server Side Request Forgery

We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).

Profile Photo
StasonJatham/cisco-sa-sma-attack-N9bf4

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

cisco cve sma cve-2025-20393

Python

Updated: 1 hour, 56 minutes ago
3 stars 0 fork 0 watcher
Born at : Dec. 18, 2025, 12:55 p.m. This repo has been linked 1 different CVEs too.
Profile Photo
b1gchoi/CVE-2025-20393

None

Updated: 4 hours, 40 minutes ago
0 stars 0 fork 0 watcher
Born at : Dec. 18, 2025, 12:29 p.m. This repo has been linked 1 different CVEs too.
Profile Photo
KingHacker353/CVE-2025-20393

None

Updated: 5 hours, 33 minutes ago
0 stars 0 fork 0 watcher
Born at : Dec. 18, 2025, 12:10 p.m. This repo has been linked 1 different CVEs too.
Profile Photo
cyberleelawat/CVE-2025-20393

Cisco is aware of a potential vulnerability.  Cisco is currently investigating and will update these details as appropriate as more information becomes available.

Updated: 6 hours, 42 minutes ago
0 stars 0 fork 0 watcher
Born at : Dec. 18, 2025, 10:02 a.m. This repo has been linked 1 different CVEs too.
Profile Photo
thesystemowner/CVE-2025-20393-POC

This scanner detects Cisco SEG/SEWM appliances vulnerable to CVE-2025-20393, a critical unauthenticated RCE vulnerability in Cisco AsyncOS affecting devices with Spam Quarantine feature exposed to the internet. CVSS Score: 10.0 (Critical)

Python

Updated: 9 hours, 22 minutes ago
1 stars 0 fork 0 watcher
Born at : Dec. 18, 2025, 7:25 a.m. This repo has been linked 1 different CVEs too.

Results are limited to the first 15 repositories due to potential performance issues.

The following list is the news that have been mention CVE-2025-20393 vulnerability anywhere in the article.

  • TheCyberThrone
Cisco Hits Perfect 10 with Secure Email Gateway Bug

Cisco’s CVE-2025-20393 is a CVSS 10.0 zero-day in Cisco AsyncOS that gives unauthenticated attackers full root control over Cisco Secure Email Gateway and Secure Email and Web Manager when the Spam Qu ... Read more

Published Date: Dec 18, 2025 (3 hours, 4 minutes ago)
  • security.nl
CISA verplicht Amerikaanse overheid om kritiek Cisco-lek binnen week te mitigeren

Het Amerikaanse cyberagentschap CISA heeft overheidsinstanties verplicht om een aangevallen kritieke kwetsbaarheid in de Cisco Secure Email Gateway en Cisco Secure Email & Web Manager binnen een week ... Read more

Published Date: Dec 18, 2025 (6 hours, 33 minutes ago)
  • The Cyber Express
Cisco Warns of Active Cyberattack Exploiting Critical AsyncOS Vulnerability

Cisco has identified an ongoing cyberattack campaign exploiting vulnerabilities in a subset of its appliances running Cisco AsyncOS Software. The attack specifically affects Cisco Secure Email Gateway ... Read more

Published Date: Dec 18, 2025 (8 hours, 36 minutes ago)
  • The Hacker News
Cisco Warns of Active Attacks Exploiting Unpatched 0-Day in AsyncOS Email Security Appliances

Dec 18, 2025Ravie LakshmananVulnerability / Network Security Cisco has alerted users of a maximum-severity zero-day flaw in Cisco AsyncOS software that has been actively exploited by a China-nexus a ... Read more

Published Date: Dec 18, 2025 (13 hours, 38 minutes ago)
  • Daily CyberSecurity
CISA Alert: Chinese Hackers Weaponize CVSS 10 Cisco Zero-Day & SonicWall Exploit Chains

The Cybersecurity and Infrastructure Security Agency (CISA) has issued an urgent directive adding three critical vulnerabilities to its Known Exploited Vulnerabilities (KEV) catalog, signaling that ha ... Read more

Published Date: Dec 18, 2025 (15 hours, 6 minutes ago)
  • Daily CyberSecurity
Cisco Zero-Day Siege: Chinese Group UAT-9686 Deploys ‘Aqua’ Malware via CVSS 10 Root Exploit

A critical zero-day vulnerability in Cisco’s secure email appliances is under active siege by a sophisticated Chinese hacking group, granting them total control over sensitive network gateways. The ca ... Read more

Published Date: Dec 18, 2025 (15 hours, 55 minutes ago)
  • The Register
Attacks pummeling Cisco AsyncOS 0-day since late November

Suspected Chinese-government-linked threat actors have been battering a maximum-severity Cisco AsyncOS zero-day vulnerability in some Secure Email Gateway (SEG) and Secure Email and Web Manager (SEWM) ... Read more

Published Date: Dec 17, 2025 (18 hours, 56 minutes ago)
  • Help Net Security
Cisco email security appliances rooted and backdoored via still unpatched zero-day

A suspected Chinese-nexus threat group has been compromising Cisco email security devices and planting backdoors and log-purging tools on them since at least late November 2025, Cisco Talos researcher ... Read more

Published Date: Dec 17, 2025 (22 hours, 19 minutes ago)
  • BleepingComputer
Cisco warns of unpatched AsyncOS zero-day exploited in attacks

​Cisco warned customers today of an unpatched, maximum-severity Cisco AsyncOS zero-day actively exploited in attacks targeting Secure Email Gateway (SEG) and Secure Email and Web Manager (SEWM) applia ... Read more

Published Date: Dec 17, 2025 (23 hours, 2 minutes ago)
  • security.nl
Cisco waarschuwt voor misbruik van kritiek lek in Secure Email Gateway

Aanvallers maken actief misbruik van een kritieke kwetsbaarheid voor het aanvallen van Cisco Secure Email Gateway en Cisco Secure Email & Web Manager en een beveiligingsupdate is niet beschikbaar, zo ... Read more

Published Date: Dec 17, 2025 (1 day, 1 hour ago)

Results are limited to the first 20 news articles due to potential performance issues.

The following table lists the changes that have been made to the CVE-2025-20393 vulnerability over time.

Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.

  • Initial Analysis by [email protected]

    Dec. 18, 2025

    Action Type Old Value New Value
    Added CPE Configuration AND OR *cpe:2.3:o:cisco:asyncos:*:*:*:*:*:*:*:* versions up to (including) 16.0.3-044 OR cpe:2.3:h:cisco:secure_email_and_web_manager_m195:-:*:*:*:*:*:*:* cpe:2.3:h:cisco:secure_email_and_web_manager_m395:-:*:*:*:*:*:*:* cpe:2.3:h:cisco:secure_email_and_web_manager_m695:-:*:*:*:*:*:*:* cpe:2.3:h:cisco:secure_email_and_web_manager_m170:-:*:*:*:*:*:*:* cpe:2.3:h:cisco:secure_email_and_web_manager_m190:-:*:*:*:*:*:*:* cpe:2.3:h:cisco:secure_email_and_web_manager_m380:-:*:*:*:*:*:*:* cpe:2.3:h:cisco:secure_email_and_web_manager_m390:-:*:*:*:*:*:*:* cpe:2.3:h:cisco:secure_email_and_web_manager_m390x:-:*:*:*:*:*:*:* cpe:2.3:h:cisco:secure_email_and_web_manager_m680:-:*:*:*:*:*:*:* cpe:2.3:h:cisco:secure_email_and_web_manager_m690:-:*:*:*:*:*:*:* cpe:2.3:h:cisco:secure_email_and_web_manager_m690x:-:*:*:*:*:*:*:* cpe:2.3:a:cisco:secure_email_and_web_manager_virtual_appliance_m100v:-:*:*:*:*:*:*:* cpe:2.3:a:cisco:secure_email_and_web_manager_virtual_appliance_m300v:-:*:*:*:*:*:*:* cpe:2.3:a:cisco:secure_email_and_web_manager_virtual_appliance_m600v:-:*:*:*:*:*:*:* cpe:2.3:a:cisco:secure_email_gateway_virtual_appliance_c100v:-:*:*:*:*:*:*:* cpe:2.3:a:cisco:secure_email_gateway_virtual_appliance_c300v:-:*:*:*:*:*:*:* cpe:2.3:a:cisco:secure_email_gateway_virtual_appliance_c600v:-:*:*:*:*:*:*:* cpe:2.3:h:cisco:secure_email_gateway_c195:-:*:*:*:*:*:*:* cpe:2.3:h:cisco:secure_email_gateway_c395:-:*:*:*:*:*:*:* cpe:2.3:h:cisco:secure_email_gateway_c695:-:*:*:*:*:*:*:*
    Added Reference Type Cisco Systems, Inc.: https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-sma-attack-N9bf4 Types: Vendor Advisory
    Added Reference Type CISA-ADP: https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2025-20393 Types: US Government Resource
  • CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0

    Dec. 17, 2025

    Action Type Old Value New Value
    Added Reference https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2025-20393
  • New CVE Received by [email protected]

    Dec. 17, 2025

    Action Type Old Value New Value
    Added Description Cisco is aware of a potential vulnerability.  Cisco is currently investigating and will update these details as appropriate as more information becomes available.
    Added CVSS V3.1 AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H
    Added CWE CWE-20
    Added Reference https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-sma-attack-N9bf4
EPSS is a daily estimate of the probability of exploitation activity being observed over the next 30 days. Following chart shows the EPSS score history of the vulnerability.
Vulnerability Scoring Details
Base CVSS Score: 10.0
Attack Vector
Attack Complexity
Privileges Required
User Interaction
Scope
Confidentiality Impact
Integrity Impact
Availability Impact