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

published 2021-01-13 5 y ago modified 2026-06-17 4 mo ago also EUVD-2021-26383

cvss: 4.3; version 3.1, CNA
cisa kev: Not listed; not in CISA's catalog
epss: 0.5%; EPSS 0.5% chance of exploitation in 30 days, percentile 46%
public exploits: 0; none known

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.

Patch / fix

fixed in 1

Palo Alto Networks PAN-OS 8.1.18, 9.0.12, 9.1.5

Exploit prediction

0.55% chance of exploitation in the next 30 days, higher than 46% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by	version	score	vector
CNA	3.1	4.3	CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
NVD	2.0	3.3	AV:A/AC:L/Au:N/C:P/I:N/A:N

Affected products

Palo Alto Networks PAN-OS

Classification

Weakness

CWE-200 Exposure of Sensitive Information to an Unauthorized Actor
CWE-212 Improper Removal of Sensitive Information Before Storage or Transfer

Technology feeds

Palo Alto PAN-OS rss critical rss

References

security.paloaltonetworks.com /CVE-2021-3031
vendor-advisory

Sources

CVE List CVE-2021-3031
NVD CVE-2021-3031

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Summary