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.
|PAN-OS 10.0||< 10.0.6||>= 10.0.6|
|PAN-OS 9.1||< 9.1.10||>= 9.1.10|
|PAN-OS 9.0||< 9.0.14||>= 9.0.14|
|PAN-OS 8.1||< 8.1.20||>= 8.1.20|
CVSSv3.1 Base Score: 6.5 (CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:N/A:H)
Palo Alto Networks is not aware of any malicious attempts to exploit this vulnerability.
This issue is fixed in PAN-OS 8.1.20, PAN-OS 9.0.14, PAN-OS 9.1.10, PAN-OS 10.0.6, and all later PAN-OS versions.
Enable signatures for Unique Threat ID 91588 on traffic destined for the web interface to block attacks against CVE-2021-3055.
This issue requires the attacker to have authenticated access to the PAN-OS web interface. You can mitigate the impact of this issue by following best practices for securing the PAN-OS web interface. Please review the Best Practices for Securing Administrative Access in the PAN-OS technical documentation at https://docs.paloaltonetworks.com/best-practices.