{"id":"CVE-2026-0300","published":"2026-05-06T19:16:35Z","modified":"2026-10-26T19:10:00Z","title":"Palo Alto Networks PAN-OS Out-of-bounds Write Vulnerability","vendor":"Palo Alto Networks","product":"PAN-OS","tier":"core","eol":null,"description":{"text":"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. \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.","provenance":"source","from":"NVD"},"summary":{"text":"A buffer overflow in the User-ID Authentication Portal (Captive Portal) service of Palo Alto Networks PAN-OS software affects PA-Series and VM-Series firewalls. An unauthenticated remote attacker who sends specially crafted packets can execute arbitrary code with root privileges, with no user interaction required; exposure is greatly reduced by restricting access to the portal to trusted internal IP addresses.","provenance":"ai","model":"claude-haiku-5-5","generatedAt":"2026-10-23T07:12:05Z"},"cvss":{"score":9.8,"severity":"CRITICAL","version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","provenance":"source","from":"NVD"},"epss":{"score":0.41714,"percentile":0.98684,"date":"2026-10-30","provenance":"source"},"kev":{"dateAdded":"2026-05-06","dueDate":"2026-05-09","ransomware":false,"requiredAction":"Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable. Until the vendor releases an official fix, the following workaround should be implemented:  - Restrict User-ID Authentication Portal access to only trusted zones.  - Disable User-ID Authentication Portal if not required. 5/13/2026: Palo Alto has released a variety of patches. If these are relevant to your environment, please apply the designated patch.","notes":"https://security.paloaltonetworks.com/CVE-2026-0300 ; https://nvd.nist.gov/vuln/detail/CVE-2026-0300","provenance":"source"},"vulncheckKev":{"dateAdded":"2026-05-05","exploitedFirstSeen":"2026-05-05","ransomware":true,"evidence":[{"url":"https://security.paloaltonetworks.com/CVE-2026-0300","date":"2026-05-05"},{"url":"https://ransom-isac.org/blog/critical-pan-os-vulnerability/","date":"2026-05-06"},{"url":"https://unit42.paloaltonetworks.com/captive-portal-zero-day/","date":"2026-05-06"},{"url":"https://www.cisa.gov/sites/default/files/feeds/known_exploited_vulnerabilities.json","date":"2026-05-06"},{"url":"https://www.proofpoint.com/us/blog/threat-insight/more-cves-same-playbook-2026-vulnerability-exploitation-wild","date":"2026-05-27"},{"url":"https://www.cyfirma.com/research/tracking-ransomware-may-2026/","date":"2026-06-08"},{"url":"https://cyble.com/reports/H1-2026-Global-Threat-Landscape-Report.pdf","date":"2026-07-27"},{"url":"https://www.tenable.com/blog/the-agentic-ai-threat-cluster-seven-incidents-three-actors-and-what-they-mean","date":"2026-08-14"},{"url":"https://www.recordedfuture.com/blog/august-2026-cve-landscape","date":"2026-09-08"},{"url":"https://ti.qianxin.com/uploads/2026/10/29/20ab59a356a884498644cff73d47a13a.pdf","date":"2026-10-29"}],"evidenceTotal":10,"provenance":"source"},"exploited":true,"otx":{"pulseCount":50,"pulses":[{"name":"Actively_Exploited_Kev | Oct 30, 2026","url":"https://otx.alienvault.com/pulse/6ae35d889ea92b4ce19c2680","created":"2026-10-29"},{"name":"INC and The Gentlemen Ransomware: Exposed AI Infrastructure","url":"https://otx.alienvault.com/pulse/6ae254acfd783d5b63290659","created":"2026-10-28"},{"name":"Actively_Exploited_Kev | Oct 29, 2026","url":"https://otx.alienvault.com/pulse/6ae20c1db17e7057ae7d9ad1","created":"2026-10-28"},{"name":"Actively_Exploited_Kev | Oct 28, 2026","url":"https://otx.alienvault.com/pulse/6ae0ba7e0e2a97ff7b218819","created":"2026-10-27"},{"name":"Actively_Exploited_Kev | Oct 27, 2026","url":"https://otx.alienvault.com/pulse/6adf68b85c3e852f3c111d18","created":"2026-10-26"},{"name":"Actively_Exploited_Kev | Oct 24, 2026","url":"https://otx.alienvault.com/pulse/6adb740e397c3ad4799aa4cd","created":"2026-10-23"},{"name":"Actively_Exploited_Kev | Oct 23, 2026","url":"https://otx.alienvault.com/pulse/6ada236fcfba2dfa730ea482","created":"2026-10-22"},{"name":"INC and The Gentlemen Ransomware: Exposed AI Infrastructure","url":"https://otx.alienvault.com/pulse/6ad8db024c84442cd0085496","created":"2026-10-21"},{"name":"Actively_Exploited_Kev | Oct 22, 2026","url":"https://otx.alienvault.com/pulse/6ad8d33a077cbb5cab524d80","created":"2026-10-21"},{"name":"Actively_Exploited_Kev | Oct 21, 2026","url":"https://otx.alienvault.com/pulse/6ad78130c4d1ac2be83a8b6d","created":"2026-10-20"}],"provenance":"machine"},"cwes":[{"id":"CWE-787","name":"Out-of-bounds Write"}],"references":[{"url":"https://security.paloaltonetworks.com/CVE-2026-0300","tags":["Mitigation","Vendor Advisory"]},{"url":"https://cert-portal.siemens.com/productcert/html/ssa-967325.html","tags":["Third Party Advisory"]},{"url":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-0300","tags":["US Government Resource"]}],"techniques":[{"id":"T1190","name":"Exploit Public-Facing Application","tactics":["initial-access"],"provenance":"ai","basis":"ai-mapping","bases":["ai-mapping"],"basisDetail":"claude-haiku-5-5: Unauthenticated network exploit against public-facing service","mappingType":"exploitation_technique","evidence":[{"from":"description","quote":"allows an unauthenticated attacker to execute arbitrary code with root privileges","start":137,"end":218}],"model":"claude-haiku-5-5","confidence":"medium","confidenceNote":"AI-mapped from the description (quote-validated, not expert-reviewed)"},{"id":"T1059","name":"Command and Scripting Interpreter","tactics":["execution"],"provenance":"ai","basis":"ai-mapping","bases":["ai-mapping"],"basisDetail":"claude-haiku-5-5: Arbitrary code execution as root","mappingType":"primary_impact","evidence":[{"from":"description","quote":"allows an unauthenticated attacker to execute arbitrary code with root privileges","start":137,"end":218}],"model":"claude-haiku-5-5","confidence":"medium","confidenceNote":"AI-mapped from the description (quote-validated, not expert-reviewed)"}],"reports":[],"affected":[],"advisories":[],"euvd":{"id":"EUVD-2026-27879","url":"https://euvd.enisa.europa.eu/vulnerability/EUVD-2026-27879","exploited":true,"exploitedSince":"2026-05-06","provenance":"source"},"exploits":[],"exploitSources":{"pocGithub":{"count":10,"skipped":0,"earliest":"2026-05-06","earliestUrl":"https://github.com/qassam-315/PAN-OS-User-ID-Buffer-Overflow-PoC","repos":[{"name":"p3Nt3st3r-sTAr/CVE-2026-0300-POC","url":"https://github.com/p3Nt3st3r-sTAr/CVE-2026-0300-POC","stars":22,"created":"2026-05-06"},{"name":"matad0r-maghribi/CVE-2026-0300-PANOS","url":"https://github.com/matad0r-maghribi/CVE-2026-0300-PANOS","stars":4,"created":"2026-05-06"},{"name":"qassam-315/PAN-OS-User-ID-Buffer-Overflow-PoC","url":"https://github.com/qassam-315/PAN-OS-User-ID-Buffer-Overflow-PoC","stars":3,"created":"2026-05-06"},{"name":"ridhinva/panos-captive-portal-rce","url":"https://github.com/ridhinva/panos-captive-portal-rce","stars":2,"created":"2026-05-22"},{"name":"mr-r3b00t/CVE-2026-0300","url":"https://github.com/mr-r3b00t/CVE-2026-0300","stars":1,"created":"2026-05-06"}]},"first":{"date":"2026-05-06","source":"PoC-in-GitHub","url":"https://github.com/qassam-315/PAN-OS-User-ID-Buffer-Overflow-PoC"},"provenance":"source"},"exploitRefs":[],"flow":[{"stage":"exploitation","techniques":["T1190"],"provenance":"ai"},{"stage":"primary","techniques":["T1059"],"provenance":"ai"}],"timeline":[{"date":"2026-05-05","kind":"exploited-reported","label":"Exploitation 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