CVE-2022-0028: Palo Alto Networks PAN-OS Reflected Amplification Denial-of-Service Vulnerability
- Is it exploited?
Yes. CISA added it to the Known Exploited Vulnerabilities catalog on , 12 days after the CVE record was published.
- How likely is exploitation in the next 30 days?
- 2.7%
EPSS score, percentile 85.8 of all scored records
- How severe?
- 8.6 High
CVSS v3.1 base score, given by the CNA
- What should I do?
CISA deadline . Apply updates per vendor instructions.
The CVE record links no vendor advisory, patch or mitigation.
- Which versions are affected?
Affected
- from 8.1 to before 8.1.23-h1
- from 9.0 to before 9.0.16-h3
- from 9.1 to before 9.1.14-h4
- from 10.0 to before 10.0.11-h1
- from 10.1 to before 10.1.6-h6
- from 10.2 to before 10.2.2-h2
Unaffected All; from 8.1.23-h1; from 9.0.16-h3; from 9.1.14-h4; from 10.0.11-h1; from 10.1.6-h6; and 5 more
Source: CISA Known Exploited Vulnerabilities (KEV) catalog, 2026.10.28, as of ; FIRST Exploit Prediction Scoring System (EPSS), v2026.06.15, as of ; CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of . About the data.
What to do
Required action, set by CISA
Apply updates per vendor instructions.
CISA due date for this action: .
Solution (from the CVE record)
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.
Workaround (from the CVE record)
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 advantageous to apply both the attack and flood protections. 2. (Palo Alto Networks Aporeto software only) You should not enable either of these protections if using Aporeto software; instead, wait for and install a fixed version of PAN-OS software. Packet-Based Attack Protection Workaround (Recommended) Follow the technical documentation to configure packet-based attack protection options for all defined Security zones with URL filtering enabled in the Security profile for that zone: https://docs.paloaltonetworks.com/pan-os/10-2/pan-os-admin/zone-protection-and-dos-protection/configure-zone-protection-to-increase-network-security/configure-packet-based-attack-protection The packet-based attack protection workaround will prevent the firewall from establishing TCP sessions in impacted zones when the TCP SYN packet contains data in the three-way handshake for a TCP session. Please note that this workaround may disrupt applications that use TCP Fast Open in the zone. Flood Protection (Alternate) Workaround If you instead decide to enable the flood protection workaround, first make…
Advisories and patches
The CVE record links no vendor advisory, patch or mitigation.
Linked from CISA's catalog entry
Affected products and versions
As listed in the CVE record.
| Status | Versions |
|---|---|
| Unaffected | All |
| Status | Versions |
|---|---|
| Affected | from 8.1 to before 8.1.23-h1 |
| Unaffected | from 8.1.23-h1 |
| Affected | from 9.0 to before 9.0.16-h3 |
| Unaffected | from 9.0.16-h3 |
| Affected | from 9.1 to before 9.1.14-h4 |
| Unaffected | from 9.1.14-h4 |
| Affected | from 10.0 to before 10.0.11-h1 |
| Unaffected | from 10.0.11-h1 |
| Affected | from 10.1 to before 10.1.6-h6 |
| Unaffected | from 10.1.6-h6 |
| Affected | from 10.2 to before 10.2.2-h2 |
| Unaffected | from 10.2.2-h2 |
| Status | Versions |
|---|---|
| Unaffected | 2.1 All |
| Unaffected | 2.2 All |
| Unaffected | 3.0 All |
| Unaffected | 3.1 All |
Versions the record lists as unaffected: 8.1.23-h1, 9.0.16-h3, 9.1.14-h4, 10.0.11-h1, 10.1.6-h6, 10.2.2-h2, 2.1 All, 2.2 All.
Source: CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of . About the data.
About this vulnerability
A Palo Alto Networks PAN-OS URL filtering policy misconfiguration could allow a network-based attacker to conduct reflected and amplified TCP denial-of-service (RDoS) attacks.
Summary: CISA's KEV catalog, as of .
- CISA added CVE-2022-0028 to its Known Exploited Vulnerabilities (KEV) catalog on 22 Aug 2022.
- CISA's ransomware flag for this entry is "Unknown": no evidence of ransomware use in the catalog, which is not proof of none.
- The due date CISA sets for the required action is 12 Sep 2022.
- The CVE record was published on 10 Aug 2022, 12 days before it was added to KEV.
- The CVE record carries a CVSS v3.1 base score of 8.6 (High), given by its CNA.
- FIRST's EPSS model puts the probability of exploitation in the next 30 days at 2.7% (percentile 85.8), as of 28 Oct 2026.
- CISA's SSVC assessment in the CVE record: exploitation active, automatable yes, technical impact partial.
Source: CISA Known Exploited Vulnerabilities (KEV) catalog, 2026.10.28, as of ; CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of ; FIRST Exploit Prediction Scoring System (EPSS), v2026.06.15, as of . About the data.
Description
PAN-OS: Reflected Amplification Denial-of-Service (DoS) Vulnerability in URL Filtering
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.
Source: CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of . About the data.
Weakness
CWE and CAPEC are maintained by MITRE; the entries are those named in the CVE record and the KEV entry.
Timeline
| Date | Event |
|---|---|
| CVE record published | |
| Added to CISA KEV | |
| CISA due date for the required action | |
| CVE record last updated |
References
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