CVE-2021-3031PAN-OS: Information exposure in Ethernet data frame construction (Etherleak)
- 4.3MediumCVSS base score
- 0.55%Exploitation in 30 daysEPSS · top 54% of all CVEs
- NoKnown exploitednot in CISA's KEV catalog
- NonePublic exploitsnone known yet
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.
Timeline
ID reserved
By palo_alto
- 7 days later
· 7 days later
Published
- 4 years later
· 4 years later
Record updated
Changes after publication (a new score, a public exploit, EPSS crossing 1, 10 or 50 %, leaving KEV) are kept since November 2026; earlier ones are not known.
Scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| palo_altoCNA (assigner) | 3.1 | Medium4.3 | CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N |
| NVDNVD · Modified | 3.1 | Medium4.3 | CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N |
- EPSS (exploitation in 30 days)
- 0.55% · top 54% of all CVEs (13 Nov 2026)
The list uses the assigner's score when there is one, then CISA's, then NVD's: Medium 4.3.
Affected products
- affected 8.1 – < 8.1.18
- affected 9.0 – < 9.0.12
- affected 9.1 – < 9.1.5
- unaffected 10.0.*
- unaffected 8.1.18 – < 8.1*
- unaffected 9.0.12 – < 9.0*
- unaffected 9.1.5 – < 9.1*
What to do
Solution: This issue is fixed in PAN-OS 8.1.18, PAN-OS 9.0.12, PAN-OS 9.1.5, and all later PAN-OS versions.
Workaround: There is no workaround to prevent the information leak in the Ethernet packets; however, restricting access to the networks mitigates the risk of this issue.
Exploitation: Palo Alto Networks is not aware of any malicious exploitation of this issue.
References
References1
- https://security.paloaltonetworks.com/CVE-2021-3031 (opens in a new tab)x_refsource_MISCx_transferred
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- EUVD EUVD-2021-26383 (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisories (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
Badge for a README or a ticket
[](https://cveledger.app/cve/CVE-2021-3031)Record last updated .