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CVE-2020-2021 — PAN-OS: Authentication Bypass in SAML Authentication

CVE-2020-2021 · PAN-OS · CVSS 10 · KEV

In brief

Severity · CVSS
Critical10CVSS 3.1, Critical
EPSS
4%
CISA KEV
Known exploited, listed since 25 Mar 2022
CERT-FR
No advisory or alert referenced in the catalog
Products
PAN-OS
Published · Modified
·
Last verified

Summary

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 …

Weakness: CWE-347

Title, description and the vendor's statements are quoted from the CVE record; a vendor's advisory is summarised in Patcharo's words, with a link.

Affected and fixed versions

Per product and release branch, as the vendor's CVE record and official advisory state them. A fixed release is shown only when a document names it: the vendor's, or CERT-FR's for Check Point, with its source.

3 branches with a published fixed release · 1 branch without a precise fixed release

Palo Alto Networks PAN-OS

Source: CVE-2020-2021

  1. 9.1End of life
    Affected versions>= 9.1.0, < 9.1.3
    First fixed release9.1.3
  2. 9.0End of life
    Affected versions>= 9.0.0, < 9.0.9
    First fixed release9.0.9
  3. 8.1End of life
    Affected versions>= 8.1.0, < 8.1.15
    First fixed release8.1.15
  4. 8.0End of life
    Affected versions>= 8.0.0
    First fixed releaseNot published in the sources followed
  5. 7.1End of life
    Affected versionsNot affected
    First fixed release—

Remediation

Fix available

Vendor fix

  • PAN-OS 9.19.1.3
  • PAN-OS 9.09.0.9
  • PAN-OS 8.18.1.15

Upgrade to a fixed release listed above for your branch, or to a later fixed release the vendor explicitly supports.

This issue is fixed in PAN-OS 8.1.15, PAN-OS 9.0.9, PAN-OS 9.1.3, and all later versions. Important: Ensure that the signing certificate for your SAML Identity Provider is configured as the 'Identity Provider Certificate' before you upgrade to a fixed version to ensure that your users can continue to authenticate

Full text

successfully. Configuring the 'Identity Provider Certificate' is an essential part of a secure SAML authentication configuration. https://docs.paloaltonetworks.com/pan-os/9-1/pan-os-admin/authentication/configure-saml-authentication Details of all actions required before and after upgrading PAN-OS are available in https://knowledgebase.paloaltonetworks.com/KCSArticleDetail?id=kA14u0000008UXK. To eliminate unauthorized sessions on GlobalProtect portals and gateways, Prisma Access managed through Panorama, change the certificate used to encrypt and decrypt the Authentication Over…

SourcePalo Alto Networks (CVE record)

Mitigation (vendor)

Using a different authentication method and disabling SAML authentication will completely mitigate the issue. Until an upgrade can be performed, applying both these mitigations (a) and (b) eliminates the configuration required for exposure to this vulnerability: (a) Ensure that the 'Identity Provider Certificate' is

Full text

configured. Configuring the 'Identity Provider Certificate' is an essential part of a secure SAML authentication configuration. (b) If the identity provider (IdP) certificate is a certificate authority (CA) signed certificate, then ensure that the 'Validate Identity Provider Certificate' option is enabled in the SAML Identity Provider Server Profile. Many popular IdPs generate self-signed IdP certificates by default and the 'Validate Identity Provider Certificate' option cannot be enabled. Additional steps may be required to use a certificate signed by a CA. This certificate…

SourcePalo Alto Networks (CVE record)

CISA KEV required action

Apply updates per vendor instructions.

CISA due date:

SourceCISA KEV

Vendor advisory

Sourcehttps://security.paloaltonetworks.com/CVE-2020-2021

Last verified 1 Oct 2026 at 09:30 UTC

Known exploitation

Added to CISA KEV on 25 Mar 2022

Federal remediation due date: 15 Apr 2022

Known use in ransomware campaigns

The CISA required action is shown under Remediation.

4% probability of exploitation in the next 30 days (percentile 91%).

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H

CERT-FR

No CERT-FR advisory or alert of the last two years references this CVE, for the vendors Patcharo covers.

Timeline

  1. Published by the source
  2. Added to CISA KEV
  3. CISA remediation due date
  4. Source record last modified
  5. EPSS score computed
  6. Last verified by Patcharo

Official sources

References

Palo Alto Networks · CISA Known Exploited Vulnerabilities · NVD · FIRST EPSS

How Patcharo reads this

Affected and fixed releases come from the vendor's structured statements and are matched against exact versions; CVSS from NVD, exploitation from CISA KEV and the vendor's own advisory, probability from FIRST EPSS. Missing data stays Unknown and never becomes Not affected.

Read the methodologyRead the guide: PAN-OS versions explained: release lines, maintenance releases and the -h1, -h2, -h3 suffixes

Related vulnerabilities

Other records affecting the same products, newest first.

  • CVE-2026-0301PAN-OS: Information Disclosure Vulnerability in URL FilteringHigh
  • CVE-2026-0280PAN-OS: IPv6 Firewall Policy BypassHigh
  • CVE-2026-0281PAN-OS: Information Disclosure Vulnerability in Management Web InterfaceHigh
  • CVE-2026-0283PAN-OS: Authentication Bypass Vulnerability in Large Scale VPN (LSVPN)High
  • CVE-2026-0284PAN-OS: XML Injection Vulnerability in Large Scale VPN (LSVPN)Critical

All PAN-OS vulnerabilitiesAll Palo Alto Networks vulnerabilities