CVE-2021-3048 PAN-OS: Invalid URLs in an External Dynamic List (EDL) can Lead to Firewall Outage
Description
Certain invalid URL entries contained in an External Dynamic List (EDL) cause the Device Server daemon (devsrvr) to stop responding.
This condition causes subsequent commits on the firewall to fail and prevents administrators from performing commits and configuration changes even though the firewall remains otherwise functional. If the firewall then restarts, it results in a denial-of-service (DoS) condition and the firewall stops processing traffic.
This issue impacts:
PAN-OS 9.0 versions earlier than PAN-OS 9.0.14;
PAN-OS 9.1 versions earlier than PAN-OS 9.1.9;
PAN-OS 10.0 versions earlier than PAN-OS 10.0.5.
PAN-OS 8.1 and PAN-OS 10.1 versions are not impacted.
Product Status
| Versions | Affected | Unaffected |
|---|---|---|
| PAN-OS 10.1 | None | 10.1.* |
| PAN-OS 10.0 | < 10.0.5 | >= 10.0.5 |
| PAN-OS 9.1 | < 9.1.9 | >= 9.1.9 |
| PAN-OS 9.0 | < 9.0.14 | >= 9.0.14 |
| PAN-OS 8.1 | None | 8.1.* |
Required Configuration for Exposure
This issue is applicable only if an External Dynamic List (EDL) is configured on the firewall.
An EDL that contains only domain names or IP addresses will not cause this issue.
Severity: MEDIUM
CVSSv3.1 Base Score: 5.9 (CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H)
Weakness Type
CWE-20 Improper Input Validation
Solution
This issue is fixed in PAN-OS 9.0.14, PAN-OS 9.1.9, PAN-OS 10.0.5, and all later PAN-OS versions.
If a firewall encounters this problem, you will require TAC assistance to make the firewall operational again.
Workarounds and Mitigations
You can prevent this issue by removing all invalid URL entries from source EDLs or removing the EDL from your configuration.
Additionally, do not configure EDLs from websites that you do not trust.