title: PAN-OS: Denial-of-Service (DoS) Vulnerability in DNS Proxy
description: 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.
problem types: CWE-755 Improper Handling of Exceptional Conditions
affected:
{
product: PAN-OS
vendor: Palo Alto Networks
versions:
status: unaffected, version: 10.2.*
changes: [at: 8.1.22, status: unaffected], lessThan: 8.1.22, status: affected, version: 8.1, versionType: custom
changes: [at: 9.1.13, status: unaffected], lessThan: 9.1.13, status: affected, version: 9.1, versionType: custom
changes: [at: 10.1.5, status: unaffected], lessThan: 10.1.5, status: affected, version: 10.1, versionType: custom
changes: [at: 10.0.10, status: unaffected], lessThan: 10.0.10, status: affected, version: 10.0, versionType: custom
changes: [at: 9.0.16, status: unaffected], lessThan: 9.0.16, status: affected, version: 9.0, versionType: custom
}
{
product: Prisma Access
vendor: Palo Alto Networks
versions:
status: unaffected, version: 3.0 Preferred, Innovation
status: unaffected, version: 2.2 Preferred
status: unaffected, version: 2.1 Preferred, Innovation
}
metrics:
cvssV3_1: [
attackComplexity: HIGH
attackVector: NETWORK
availabilityImpact: HIGH
baseScore: 5.9
baseSeverity: MEDIUM
confidentialityImpact: NONE
integrityImpact: NONE
privilegesRequired: NONE
scope: UNCHANGED
userInteraction: NONE
vectorString: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
version: 3.1
]
exploits: Palo Alto Networks is not aware of any malicious exploitation of this issue.
solutions: 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: 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.