Palo Alto Networks Security Advisories / CVE-2021-3048

CVE-2021-3048 PAN-OS: Invalid URLs in an External Dynamic List (EDL) can Lead to Firewall Outage

047910
Severity 5.9 · MEDIUM
Attack Vector NETWORK
Attack Complexity HIGH
Privileges Required NONE
User Interaction NONE
Scope UNCHANGED
Confidentiality Impact NONE
Integrity Impact NONE
Availability Impact HIGH

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

VersionsAffectedUnaffected
PAN-OS 10.1None10.1.*
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 8.1None8.1.*

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.

Acknowledgments

This issue was encountered by some customers of Palo Alto Networks during regular operation.

Timeline

Initial publication
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