CVE-2021-3055: Palo Alto Networks PAN-OS

Medium severity, CVSS 6.5. EPSS: 1.1% chance of exploitation in the next 30 days.

An improper restriction of XML external entity (XXE) reference vulnerability in the Palo Alto Networks PAN-OS web interface enables an authenticated administrator to read any arbitrary file from the file system and send a specifically crafted request to the firewall that causes the service to crash. Repeated attempts to send this request result in denial of service to all PAN-OS services by restarting the device and putting it into maintenance mode. This issue impacts: PAN-OS 8.1 versions earlier than PAN-OS 8.1.20; PAN-OS 9.0 versions earlier than PAN-OS 9.0.14; PAN-OS 9.1 versions earlier than PAN-OS 9.1.10; PAN-OS 10.0 versions earlier than PAN-OS 10.0.6. This issue does not affect Prisma Access.

Affected products

• Palo Alto Networks PAN-OS: from 8.1.0, before 8.1.20 (fixed in 8.1.20); from 9.0.0, before 9.0.14 (fixed in 9.0.14); from 9.1.0, before 9.1.10 (fixed in 9.1.10); from 10.0.0, before 10.0.6 (fixed in 10.0.6)

Published 2021-09-08. Last modified 2026-06-17.