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 (CWE-787) involves an out-of-bounds write in the User-ID Authentication Portal (Captive Portal) service of Palo Alto Networks PAN-OS software. An unauthenticated attacker can exploit this buffer overflow to execute arbitrary code with root privileges on PA-Series and VM-Series firewalls. The vulnerability does not impact Prisma Access, Cloud NGFW, or Panorama appliances. The vendor recommends restricting access to the User-ID Authentication Portal to trusted internal IP addresses to reduce risk. No patch or official remediation has been disclosed at this time.
Potential Impact
Successful exploitation allows unauthenticated attackers to execute arbitrary code with root privileges on affected PA-Series and VM-Series firewalls, potentially leading to full system compromise. Prisma Access, Cloud NGFW, and Panorama appliances are not impacted by this vulnerability.
Mitigation Recommendations
No official patch or remediation level has been confirmed yet. The vendor recommends reducing risk by restricting access to the User-ID Authentication Portal to trusted internal IP addresses as per 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.
CVSS v4.0
Score 9.3critical
Weaknesses
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
This vulnerability (CWE-787) involves an out-of-bounds write in the User-ID Authentication Portal (Captive Portal) service of Palo Alto Networks PAN-OS software. An unauthenticated attacker can exploit this buffer overflow to execute arbitrary code with root privileges on PA-Series and VM-Series firewalls. The vulnerability does not impact Prisma Access, Cloud NGFW, or Panorama appliances. The vendor recommends restricting access to the User-ID Authentication Portal to trusted internal IP addresses to reduce risk. No patch or official remediation has been disclosed at this time.
Potential Impact
Successful exploitation allows unauthenticated attackers to execute arbitrary code with root privileges on affected PA-Series and VM-Series firewalls, potentially leading to full system compromise. Prisma Access, Cloud NGFW, and Panorama appliances are not impacted by this vulnerability.
Mitigation Recommendations
No official patch or remediation level has been confirmed yet. The vendor recommends reducing risk by restricting access to the User-ID Authentication Portal to trusted internal IP addresses as per 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: 05/06/2026, 19:06:25 UTC
Last enriched: 07/15/2026, 11:21:56 UTC
Last updated: 07/31/2026, 19:22:57 UTC
Views: 218
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