PAN-OS: Reflected Amplification Denial-of-Service (DoS) Vulnerability in URL Filtering
- Severity
- High8.6CVSS 3.1, High
- EPSS
- 2%
- Published
- 10 Aug 2022
- Updated
- 17 Jun 2026
Description
Title, description and vendor guidance are quoted from the source records.
A PAN-OS URL filtering policy misconfiguration could allow a network-based attacker to conduct reflected and amplified TCP denial-of-service (RDoS) attacks. The DoS attack would appear to originate from a Palo Alto Networks PA-Series (hardware), VM-Series (virtual) and CN-Series (container) firewall against an attacker-specified target. To be misused by an external attacker, the firewall configuration must have a URL filtering profile with one or more blocked categories assigned to a source zone that has an external facing interface. This configuration is not typical for URL filtering and, if set, is likely unintended by the administrator. If exploited, this issue would not impact the confidentiality, integrity, or availability of our products. However, the resulting denial-of-service (DoS) attack may help obfuscate the identity of the attacker and implicate the firewall as the source of the attack. We have taken prompt action to address this issue in our PAN-OS software. All software updates for this issue are expected to be released no later than the week of August 15, 2022. This issue does not impact Panorama M-Series or Panorama virtual appliances. This issue has been resolved for all Cloud NGFW and Prisma Access customers and no additional action is required from them.
Weakness: CWE-406
Known exploited
Added to CISA KEV on 22 Aug 2022
Federal remediation due date: 12 Sept 2022
Required action: Apply updates per vendor instructions.
Exploit prediction
2% probability of exploitation in the next 30 days (percentile 83%).
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H
What the source states, per branch
Versions matched by Patcharo
Palo Alto Networks PAN-OSSource: Palo Alto Networks (CVE record)
| Branch | Affected | Fixed in |
|---|---|---|
| 10.2 | >= 10.2.0, < 10.2.2-h2 | 10.2.2-h2 |
| 10.1 | >= 10.1.0, < 10.1.6-h6 | 10.1.6-h6 |
| 10.0 | >= 10.0.0, < 10.0.11-h1 | 10.0.11-h1 |
| 9.1 | >= 9.1.0, < 9.1.14-h4 | 9.1.14-h4 |
| 9.0 | >= 9.0.0, < 9.0.16-h3 | 9.0.16-h3 |
| 8.1 | >= 8.1.0, < 8.1.23-h1 | 8.1.23-h1 |
Versions not listed are not assessed (shown as Unknown).
Workaround / Vendor remediation
Workaround · PAN-OS
If you have a URL filtering policy with one or more blocked categories assigned to a source zone that has an external facing network interface, removing this configuration will prevent this issue from being exploited by remote attackers to conduct reflected DoS. To prevent denial-of-service (DoS) attacks resulting from this issue from all sources, you can configure your Palo Alto Networks firewalls by enabling one of two zone protection mitigations on all Security zones with an assigned Security policy that includes a URL filtering profile: 1. Packet-based attack protection including both (Packet Based Attack Protection > TCP Drop > TCP SYN with Data) and (Packet Based Attack Protection > TCP Drop > Strip TCP Options > TCP Fast Open); OR 2. Flood protection (Flood Protection > SYN > Action > SYN Cookie) with an activation threshold of 0 connections. NOTES: 1. It is not necessary nor adv…
Vendor remediation · PAN-OS
We identified workarounds to prevent the denial-of-service (DoS) attacks that result from this issue in certain Palo Alto Networks firewalls, with this policy configuration We intend to fix this issue for PA-Series, VM-Series and CN-Series firewalls with a fix in the following PAN-OS software releases: PAN-OS 8.1.23-h1 (ETA: week of August 8, 2022), PAN-OS 9.0.16-h3 (ETA: week of August 15, 2022), PAN-OS 9.1.14-h4 (ETA: week of August 15, 2022), PAN-OS 10.0.11-h1 (ETA: week of August 15, 2022), PAN-OS 10.1.6-h6 (ETA: week of August 8, 2022), and PAN-OS 10.2.2-h2 (ETA: week of August 15, 2022). We expect to release all PAN-OS software updates for this issue no later than the week of August 15, 2022.
References
Provenance
Every fact on this page comes from the sources below. Nothing is written by an AI.
- Palo Alto Networks (CVE record)
- Palo Alto Networks (CVE record) · 27 Sept 2026, 23:46 UTC · Parser patcharo-cve5/1.1.0
- CISA Known Exploited Vulnerabilities
- CISA Known Exploited Vulnerabilities · 27 Sept 2026, 23:42 UTC · Parser patcharo-kev/1.0.0
- NVD
- NVD · 27 Sept 2026, 23:44 UTC · Parser patcharo-nvd/1.0.0
- FIRST EPSS
- FIRST EPSS · 27 Sept 2026, 23:46 UTC · Parser patcharo-epss/1.0.0
Last verified: 28 Sept 2026, 02:31 UTC