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Vulnerabilities

Vulnerability · CVE-2020-2021

Palo Alto Networks PAN-OS Authentication Bypass Vulnerability

Published Jun 29, 2020 · catalog updated Jun 16, 2026 · Palo Alto Networks PAN-OS

Patch now

CVE-2020-2021 is in the CISA known-exploited catalog, due Apr 15, 2022. Confirm Palo Alto Networks PAN-OS against the vendor advisory and apply that fix. The CVSS score does not change the priority.

Gaps on this record

  • No version range is stored. A customer cannot check an installed version against this record.
Severity
Critical10.0
Known exploitation
CISA KEV and VulnCheck KEV
EPSS
4.36%
Remediation
Remediation guidance
Affected products
cpe paloaltonetworks/pan-os · vendor Palo Alto Networks PAN-OS

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

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  • cpe paloaltonetworks/pan-osversion unspecified
  • vendor Palo Alto Networks PAN-OSversion unspecified

How to fix CVE-2020-2021

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

CVE-2020-2021 is in the CISA known-exploited catalog, due Apr 15, 2022. Confirm Palo Alto Networks PAN-OS against the vendor advisory and apply that fix. The CVSS score does not change the priority.

Which versions are affected?

Affected version ranges are not on this record. Apply updates per vendor instructions.

What should an analyst verify?

CWE-347: Improper Verification of Cryptographic Signature. EPSS 4.36%. The CISA KEV listing is the exploitation evidence. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Code

The project this record applies to. Exploit listings stay in References.

No public source repository is identified for this product.

Timeline

Detection, updates, and resolution for this record.

  1. Jun 29, 2020 · Catalog

    Detected

    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

  2. Mar 25, 2022 · CISA KEV

    Known exploited

    Apply updates per vendor instructions.

  3. Apr 15, 2022 · CISA KEV

    Remediation due

    Apply updates per vendor instructions.

  4. Jun 16, 2026 · Catalog

    Updated

    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

Sources

  • CISA KEVConfirmed exploitationCVE-2020-2021

    Palo Alto Networks PAN-OS contains a vulnerability in SAML which allows an attacker to bypass authentication.

    cisa.gov
  • CVE.orgVulnerability recordCVE-2020-2021

    Official CVE identifier

    cve.org
  • FIRST EPSSExploitation probabilityCVE-2020-2021

    30-day exploitation probability 4.4%

    first.org
  • NIST NVDVulnerability recordCVE-2020-2021

    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

    nvd.nist.gov
  • VulnCheck KEVConfirmed exploitationCVE-2020-2021

    Palo Alto Networks PAN-OS contains a vulnerability in SAML which allows an attacker to bypass authentication.

    vulncheck.com

References

Freshness

Last verified in this catalog Oct 17, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.