CVE-2026-0300: CWE-787: Out-of-bounds Write in Palo Alto Networks Cloud NGFW
A buffer overflow vulnerability in the User-ID™ Authentication Portal (aka Captive Portal) service of Palo Alto Networks PAN-OS software allows an unauthenticated attacker to execute arbitrary code with root privileges on the PA-Series and VM-Series firewalls by sending specially crafted packets. The risk of this issue is greatly reduced if you secure access to the User-ID™ Authentication Portal per the best practice guidelines https://knowledgebase.paloaltonetworks.com/KCSArticleDetail by restricting access to only trusted internal IP addresses. Prisma Access, Cloud NGFW and Panorama appliances are not impacted by this vulnerability.
AI Analysis
Technical Summary
This vulnerability (CVE-2026-0300) is a buffer overflow (CWE-787) in the User-ID Authentication Portal service of Palo Alto Networks PAN-OS software on PA-Series and VM-Series firewalls. It allows unauthenticated remote attackers to execute arbitrary code with root privileges by sending specially crafted packets. The Cloud NGFW product itself is not impacted. The vulnerability has a CVSS 4.0 score of 9.3, indicating critical severity. No patch or official remediation has been published yet. Mitigation involves restricting access to the vulnerable service to trusted internal IP addresses following vendor best practices. Prisma Access, Cloud NGFW, and Panorama appliances are not affected.
Potential Impact
Successful exploitation results in remote code execution with root privileges on affected PA-Series and VM-Series firewalls. This could lead to full compromise of the firewall device. However, Prisma Access, Cloud NGFW, and Panorama appliances are not impacted. There are no known exploits in the wild at this time.
Mitigation Recommendations
No official patch or remediation level has been confirmed yet. Palo Alto Networks recommends reducing risk by restricting access to the User-ID Authentication Portal to trusted internal IP addresses according to their best practice guidelines. Monitor the vendor advisory for updates on patch availability and apply official fixes once released.
CVE-2026-0300: CWE-787: Out-of-bounds Write in Palo Alto Networks Cloud NGFW
Description
A buffer overflow vulnerability in the User-ID™ Authentication Portal (aka Captive Portal) service of Palo Alto Networks PAN-OS software allows an unauthenticated attacker to execute arbitrary code with root privileges on the PA-Series and VM-Series firewalls by sending specially crafted packets. The risk of this issue is greatly reduced if you secure access to the User-ID™ Authentication Portal per the best practice guidelines https://knowledgebase.paloaltonetworks.com/KCSArticleDetail by restricting access to only trusted internal IP addresses. Prisma Access, Cloud NGFW and Panorama appliances are not impacted by this vulnerability.
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
This vulnerability (CVE-2026-0300) is a buffer overflow (CWE-787) in the User-ID Authentication Portal service of Palo Alto Networks PAN-OS software on PA-Series and VM-Series firewalls. It allows unauthenticated remote attackers to execute arbitrary code with root privileges by sending specially crafted packets. The Cloud NGFW product itself is not impacted. The vulnerability has a CVSS 4.0 score of 9.3, indicating critical severity. No patch or official remediation has been published yet. Mitigation involves restricting access to the vulnerable service to trusted internal IP addresses following vendor best practices. Prisma Access, Cloud NGFW, and Panorama appliances are not affected.
Potential Impact
Successful exploitation results in remote code execution with root privileges on affected PA-Series and VM-Series firewalls. This could lead to full compromise of the firewall device. However, Prisma Access, Cloud NGFW, and Panorama appliances are not impacted. There are no known exploits in the wild at this time.
Mitigation Recommendations
No official patch or remediation level has been confirmed yet. Palo Alto Networks recommends reducing risk by restricting access to the User-ID Authentication Portal to trusted internal IP addresses according to their best practice guidelines. Monitor the vendor advisory for updates on patch availability and apply official fixes once released.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- palo_alto
- Date Reserved
- 2025-11-03T20:44:58.173Z
- Cvss Version
- 4.0
- State
- PUBLISHED
- Remediation Level
- null
Threat ID: 69fb9131cbff5d86102f43a4
Added to database: 5/6/2026, 7:06:25 PM
Last enriched: 5/6/2026, 7:21:52 PM
Last updated: 5/7/2026, 3:08:13 AM
Views: 15
Community Reviews
0 reviewsCrowdsource mitigation strategies, share intel context, and vote on the most helpful responses. Sign in to add your voice and help keep defenders ahead.
Want to contribute mitigation steps or threat intel context? Sign in or create an account to join the community discussion.
Actions
Updates to AI analysis require Pro Console access. Upgrade inside Console → Billing.
Need more coverage?
Upgrade to Pro Console for AI refresh and higher limits.
For incident response and remediation, OffSeq services can help resolve threats faster.
Latest Threats
Check if your credentials are on the dark web
Instant breach scanning across billions of leaked records. Free tier available.