CVE-2020-2021
10, critical Known exploited Used in ransomwarePalo Alto Networks PAN-OS Authentication Bypass Vulnerability
- CVSS
- 10, critical critical CVSS v3.1
- EPSS, next 30 days
- 4% higher than 91.1% of scored CVEs
- Exploitation
- Confirmed in the wild
- Published
- 29 Jun 20206 years ago
Known exploited
CISA added this to the Known Exploited Vulnerabilities Catalog on 25 Mar 2022 and links it to ransomware activity. US federal agencies had to remediate by 15 Apr 2022, a deadline that has passed.
Required action. Apply updates per vendor instructions.
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.
Details
- Vendor
- Palo Alto Networks
- Product
- PAN-OS
- Weakness
- CWE-347 (opens in a new tab)
- Status
- Analyzed
- Updated
- 17 Jun 2026
- Assigner
- psirt@paloaltonetworks.com
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H
References 2
The kind is read from NVD's tags where present and from the shape of the URL otherwise, so treat it as a hint.
Other Palo Alto Networks CVEs
Every Palo Alto Networks CVE we holdSame vendor in what we hold, not a known link between the flaws.
- CVE-2026-0322 Palo Alto Networks PAN-OS Code Injection Vulnerability KEV EPSS 1% 7.2, high
- CVE-2026-0257 Palo Alto Networks PAN-OS Authentication Bypass Vulnerability KEV EPSS 97% 9.1, critical
- CVE-2026-0300 Palo Alto Networks PAN-OS Out-of-bounds Write Vulnerability KEV EPSS 32% 9.8, critical
- CVE-2025-0108 Palo Alto Networks PAN-OS Authentication Bypass Vulnerability KEV EPSS 98% 9.1, critical
- CVE-2025-0111 Palo Alto Networks PAN-OS File Read Vulnerability KEV EPSS 2% 6.5, medium
- CVE-2024-3393 Palo Alto Networks PAN-OS Malicious DNS Packet Vulnerability KEV EPSS 29% 7.5, high
- CVE-2024-0012 Palo Alto Networks PAN-OS Management Interface Authentication Bypass Vulnerability KEV EPSS 100% 9.8, critical
- CVE-2024-9474 Palo Alto Networks PAN-OS Management Interface OS Command Injection Vulnerability KEV EPSS 95% 7.2, high
Beyond this page
Is CVE-2020-2021 in your network?
This page tells you how dangerous CVE-2020-2021 is out there. Whether it sits on one of your devices, only a scan of your own network can tell. That is what our systems do, every day, for the companies we protect.
CVE-2020-2021 is in the CISA catalogue of exploited vulnerabilities: attackers are already exploiting it.
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Assembled from the NVD 2.0 API, the CISA Known Exploited Vulnerabilities Catalog and FIRST EPSS. Scores are as of our last collection on 18 Oct 2026, not the live upstream state.