# What is CVE-2020-2021?

> CVE-2020-2021 is a critical-severity flaw (CVSS 10.0) in PAN-OS from Palo Alto Networks, published on 29 June 2020. It is on the list of flaws known to be exploited, so criminals are already using it. The latest forecast puts its chance of use in the next 30 days at 4.4%. If you run an affected version, patch it first.

Canonical page: https://www.precursorintelligence.com/what-is/cve-2020-2021

## At a glance

- **Verdict:** Fix this now. Attackers are using this flaw today. If you run an affected version, it goes to the top of your list.
- **Precursor Intelligence risk score:** 88 out of 100 (Critical); action: Emergency patch. Kept up to date as the evidence changes.
- **Severity:** Critical (CVSS 10.0 out of 10)
- **Known to be exploited:** Yes, it is on the government list of flaws known to be exploited
- **Chance of use in the next 30 days:** 4.4% (latest exploit-likelihood forecast)
- **Published:** 29 June 2020
- **Record last updated:** 4 November 2025
- **Main product:** PAN-OS from Palo Alto Networks
- **Affected products:** 1

## What is CVE-2020-2021? In plain terms

It can be attacked from anywhere on the internet without logging in, and nobody has to click anything. If it works, the attacker can read data, change data and take it offline.

### The official 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

### What kind of flaw is it?

- CWE-347: Improper Verification of Cryptographic Signature

### How an attack on it works

- Where an attacker can be: Anywhere on the internet
- How hard it is to pull off: Easy: no special conditions
- Login needed first: No login needed
- Does someone have to click: No, nobody has to do anything
- What an attacker gets: Can read data, change data and take it offline

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

## Is CVE-2020-2021 being exploited? Yes

Attackers are already using it. It is on the government list of flaws known to be exploited, and the latest forecast puts the chance of it being used in the next 30 days at 4.4%.

Exploit likelihood over the last 7 days: 4.4%, 4.4%, 4.4%, 4.4%, 4.4%, 4.4%, 4.4%.

### Timeline

- 29 June 2020: Published
- 4 November 2025: Record last updated
- 16 June 2026: Exploit likelihood fell

### How Precursor Intelligence ranks it

CVE-2020-2021 scores **88 out of 100 (Critical)**, with the action "Emergency patch".

Every published flaw gets a risk score from 0 to 100, kept up to date as the evidence changes. Four things go into the score, from the one that counts most to the ones that count less:

- Evidence it is being exploited: biggest factor
- How severe it is: strong factor
- How widely exposed it is: smaller factor
- Threat activity around it: smaller factor

85 and above is Critical. Anything confirmed as exploited is always marked for an emergency patch, whatever its score. When this flaw matches software you track, it lands in your list with its score and the reasons behind it.

## Who is affected by CVE-2020-2021?

The published record lists 1 product. Versions are as published: "8.1.0 to before 8.1.15" means from 8.1.0 up to, but not including, 8.1.15.

- [PAN-OS](https://www.precursorintelligence.com/product/paloaltonetworks/pan-os) by [Palo Alto Networks](https://www.precursorintelligence.com/vendors/paloaltonetworks) (Operating system): 8.0.0 to 8.0.20, 8.1.0 to before 8.1.15, 9.0.0 to before 9.0.9, 9.1.0 to before 9.1.3

## How do I fix CVE-2020-2021?

1. **Check whether you run it.** Compare your versions with the affected products above. Not sure what you run? Precursor Intelligence can work it out from your public website, or you can pick it from a list.
2. **Apply the vendor’s fix.** Install the update named in the vendor’s advisory. We’ve put the advisory first in the list.
3. **If you can’t patch today.** Follow any mitigation the vendor publishes, and limit who can reach the affected system from the internet until the update is in.
4. **Check it wasn’t used before you patched.** Because criminals are already using this flaw, look for signs of a break-in on affected systems using the vendor’s guidance.

### References

- [security.paloaltonetworks.com](https://security.paloaltonetworks.com/CVE-2020-2021) (Mitigation, Vendor advisory)
- [cisa.gov](https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2020-2021) (Government resource)

## Questions

### What is CVE-2020-2021?

CVE-2020-2021 is a critical-severity flaw in PAN-OS from Palo Alto Networks, published on 29 June 2020. It can be attacked from anywhere on the internet without logging in, and nobody has to click anything. If it works, the attacker can read data, change data and take it offline.

### How serious is CVE-2020-2021?

It scores 10.0 out of 10 on the CVSS severity scale, which is critical. Our risk score for CVE-2020-2021 is 88 out of 100, which is Critical. Its action is "Emergency patch". Attackers are using this flaw today. If you run an affected version, it goes to the top of your list.

### Is CVE-2020-2021 being exploited?

Attackers are already using it. It is on the government list of flaws known to be exploited, and the latest forecast puts the chance of it being used in the next 30 days at 4.4%.

### Which versions does CVE-2020-2021 affect?

For PAN-OS from Palo Alto Networks: 8.0.0 to 8.0.20, 8.1.0 to before 8.1.15, 9.0.0 to before 9.0.9, 9.1.0 to before 9.1.3.

### How do I fix CVE-2020-2021?

Install the update the vendor names in its advisory, linked first under "How do I fix" on this page. If you can't patch today, follow the vendor's mitigation and limit who can reach the affected system from the internet. Because criminals are already using it, also check affected systems for signs of a break-in.

## Does CVE-2020-2021 affect you?

Precursor Intelligence keeps checking for you:

- **Tell us what you run.** Pick your software from a list, or let us work it out from your website.
- **We match it to every flaw.** Over 400,000 published flaws, checked against your list.
- **Ranked by real-world risk.** Every flaw gets a 0 to 100 risk score, kept up to date, led by evidence criminals are using it.
- **Told as soon as we know.** An alert by email, in the app or by webhook to your own tools.

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