{"id":"CVE-2026-0300","title":"PAN-OS: Unauthenticated user initiated Buffer Overflow Vulnerability in User-ID™ Authentication Portal","summary":"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 a…","severity":"critical","cvss":9.3,"cvssVector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:L/SI:L/SA:N/E:A/AU:Y/R:U/V:C/RE:M/U:Red","cvssSource":"cna","cwe":["CWE-787"],"vendor":"Palo Alto Networks","product":"Cloud NGFW","affected":["cloud_ngfw","PAN-OS >= 12.1.0 < 12.1.7","PAN-OS >= 11.2.0 < 11.2.12","PAN-OS >= 11.1.0 < 11.1.15","PAN-OS >= 10.2.0 < 10.2.18-h6","prisma_access"],"ssvc":{"exploitation":"active","automatable":"yes","technicalImpact":"total","timestamp":"2026-05-06T00:00:00+00:00"},"exploited":true,"exploitAvailable":true,"published":"2026-05-06","updated":"2026-10-15","sourceUpdated":"2026-10-15T01:11:55.163Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-0300","references":[{"url":"https://security.paloaltonetworks.com/CVE-2026-0300"}],"tags":["cve.org","in-the-wild","exploit-available","kev"],"epss":0.31725,"epssPercentile":0.98277,"kev":true,"kevDateAdded":"2026-05-06","kevDueDate":"2026-05-09","kevRansomware":false,"exploits":{"github":10,"githubRepos":["https://github.com/p3Nt3st3r-sTAr/CVE-2026-0300-POC","https://github.com/matad0r-maghribi/CVE-2026-0300-PANOS","https://github.com/qassam-315/PAN-OS-User-ID-Buffer-Overflow-PoC"],"checkedAt":"2026-10-15T05:53:20.620Z"},"zeroDay":true,"ingestedAt":"2026-10-15T05:52:46.052Z","slug":"CVE-2026-0300","body":"## Overview\n\nA 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. \n\nThe 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.\n\nPrisma Access, Cloud NGFW and Panorama appliances are not impacted by this vulnerability.\n\n## Affected\n\n- `cloud_ngfw`\n- `PAN-OS >= 12.1.0 < 12.1.7`\n- `PAN-OS >= 11.2.0 < 11.2.12`\n- `PAN-OS >= 11.1.0 < 11.1.15`\n- `PAN-OS >= 10.2.0 < 10.2.18-h6`\n- `prisma_access`\n\n## Remediation\n\nThis issue will be fixed in upcoming releases of PAN-OS as captured in the table above.\n\nWe strongly recommend that you secure access to your User-ID™ Authentication Portal following the instructions in the workarounds section below.\n\n### Workarounds\n\nCustomers can mitigate the risk of this issue by taking either of the following actions:\n\n * Restrict User-ID™ Authentication Portal access to only trusted zones and in addition, disable Response Pages in the Interface Management Profile attached to every L3 interface in any zone where untrusted/internet traffic can ingress. Keep Response Pages enabled only on interfaces in trust/internal zones where legitimate users' browsers ingress. Refer to Step 6 of the following Live Community article (https://live.paloaltonetworks.com/t5/general-articles/why-it-s-essential-to-secure-your-management-interface/ta-p/1001286) and Knowledgebase article (https://knowledgebase.paloaltonetworks.com/KCSArticleDetail?id=kA14u000000CqbiCAC) for steps to restrict access.\n   \n * Disable User-ID™ Authentication Portal if not required.\n   \n\nCustomers with a Threat Prevention subscription can block attacks for this vulnerability by enabling Threat ID 510019 from Applications and Threats content version 9097-10022. Decoder capabilities necessitate PAN-OS 11.1 or a later version for Threat ID support.","depth":"hadal","depthScore":82,"depthScoreParts":{"impact":51.2,"likelihood":6.3,"exploitation":25,"ransomware":0},"changes":[]}