Palo Alto Networks Security Advisories / CVE-2022-0023

CVE-2022-0023 PAN-OS: Denial-of-Service (DoS) Vulnerability in DNS Proxy

Severity 5.9 · MEDIUM
Attack Vector NETWORK
Attack Complexity HIGH
Confidentiality Impact NONE
Privileges Required NONE
Integrity Impact NONE
User Interaction NONE
Availability Impact HIGH


An improper handling of exceptional conditions vulnerability exists in the DNS proxy feature of Palo Alto Networks PAN-OS software that enables a meddler-in-the-middle (MITM) to send specifically crafted traffic to the firewall that causes the service to restart unexpectedly. Repeated attempts to send this request result in denial-of-service to all PAN-OS services by restarting the device in maintenance mode.

This issue does not impact Panorama appliances and Prisma Access customers.

This issue impacts:

PAN-OS 8.1 versions earlier than PAN-OS 8.1.22;

PAN-OS 9.0 versions earlier than PAN-OS 9.0.16;

PAN-OS 9.1 versions earlier than PAN-OS 9.1.13;

PAN-OS 10.0 versions earlier than PAN-OS 10.0.10;

PAN-OS 10.1 versions earlier than PAN-OS 10.1.5.

This issue does not impact PAN-OS 10.2.

Product Status

PAN-OS 10.2None10.2.*
PAN-OS 10.1< 10.1.5>= 10.1.5
PAN-OS 10.0< 10.0.10>= 10.0.10
PAN-OS 9.1< 9.1.13>= 9.1.13
PAN-OS 9.0< 9.0.16>= 9.0.16
PAN-OS 8.1< 8.1.22>= 8.1.22
Prisma Access 3.0NonePreferred, Innovation
Prisma Access 2.2NonePreferred
Prisma Access 2.1NonePreferred, Innovation

Required Configuration for Exposure

This issue is applicable only to PAN-OS hardware and virtual firewalls with the DNS proxy feature enabled. You can verify whether DNS proxy is enabled by selecting 'Network > DNS Proxy’ from the web interface.


CVSSv3.1 Base Score:5.9 (CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H)

Exploitation Status

Palo Alto Networks is not aware of any malicious exploitation of this issue.

Weakness Type

CWE-755 Improper Handling of Exceptional Conditions


This issue is fixed in PAN-OS 8.1.22, PAN-OS 9.0.16, PAN-OS 9.1.13, PAN-OS 10.0.10, PAN-OS 10.1.5, and all later PAN-OS versions.

Workarounds and Mitigations

Customers with a Threat Prevention subscription can block attack traffic related to this vulnerability by enabling Threat ID 92406 (Applications and Threats content update 8556).

To completely mitigate the risk of this issue, temporarily disable the DNS proxy feature until you are able to upgrade your PAN-OS software to a fixed version.


This issue was found by Nicholas Newsom of Palo Alto Networks during internal security review.


Initial publication
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