CVE-2021-3031: PAN-OS: Information exposure in Ethernet data frame construction (Etherleak)

Severity: low (CVSS 3.3 v2.0)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.5% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2021-01-13 · updated 2026-06-17
Weakness: CWE-200

Description

Padding bytes in Ethernet packets on PA-200, PA-220, PA-500, PA-800, PA-2000 Series, PA-3000 Series, PA-3200 Series, PA-5200 Series, and PA-7000 Series firewalls are not cleared before the data frame is created. This leaks a small amount of random information from the firewall memory into the Ethernet packets. An attacker on the same Ethernet subnet as the PAN-OS firewall is able to collect potentially sensitive information from these packets. This issue is also known as Etherleak and is detected by security scanners as CVE-2003-0001. This issue impacts: PAN-OS 8.1 version earlier than PAN-OS 8.1.18; PAN-OS 9.0 versions earlier than PAN-OS 9.0.12; PAN-OS 9.1 versions earlier than PAN-OS 9.1.5.

Affected products

Palo Alto Networks PAN-OS: from 8.1.0 before 8.1.18; from 9.0.0 before 9.0.12; from 9.1.0 before 9.1.5 — fixed in 8.1.18, 9.0.12, 9.1.5
Palo Alto Networks PAN-OS: from 8.1 before 8.1.18; from 9.0 before 9.0.12; from 9.1 before 9.1.5 — fixed in 8.1.18, 9.0.12, 9.1.5

How to fix

Upgrade to a fixed version: Palo Alto Networks PAN-OS 8.1.18, 9.0.12, 9.1.5; Palo Alto Networks PAN-OS 8.1.18, 9.0.12, 9.1.5. Check the vendor advisory for mitigations.

References

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