CVE-2026-0300CISA KEV

Palo Alto Networks PAN-OS Out-of-bounds Write Vulnerability

CISA lists this Palo Alto Networks PAN-OS vulnerability as known exploited. Check the cited references and original publisher guidance for affected products and remediation.

CISA KEV CISA-cited reference NVD

CISA catalog record

Palo Alto Networks PAN-OS contains an out-of-bounds write vulnerability in the User-ID Authentication Portal (aka Captive Portal) service that can allow an unauthenticated attacker to execute arbitrary code with root privileges on the PA-Series and VM-Series firewalls by sending specially crafted packets.

Product: PAN-OS
Added to KEV: 6 May 2026
Federal remediation due: 9 May 2026
Known ransomware use: Not reported

Page history

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Cite this version

Field-level log (4)

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29 Oct 2026 · 20:19:26 UTC Link: Vendor advisoryhttps://security.paloaltonetworks.com/CVE-2026-0300 → No longer listed in this observation
29 Oct 2026 · 20:19:26 UTC Link: CISA-cited referencehttps://security.paloaltonetworks.com/CVE-2026-0300
23 Oct 2026 · 09:33:49 UTC Source coverage: cisa-kevIncomplete → Current
23 Oct 2026 · 08:31:50 UTC Source coverage: cisa-kevCurrent → Incomplete

Explore global source statements, affected packages and advisory history for CVE-2026-0300. The catalog has a separate collection scope from Microsoft release records.

Collected exploitation and prediction evidence

Risk source coverage

CISA KEV is observed exploitation evidence. FIRST EPSS is a dated prediction of exploitation in the next 30 days. Missing scores are unknown. This collector requests predictions only for explicit CVE aliases in the public NuGet archive; Microsoft release views retain their existing prediction scope.

CVE-2026-0300

CISA KEV listing collected · added 6 May 2026 · Palo Alto Networks · PAN-OS

CISA source · CISA-cited reference

EPSS unknown / outside the collected prediction scope.

Observed 23 Oct 2026 16:01:26 UTC · Complete immutable risk JSON

cve-program · CVE-2026-0300

Published

PAN-OS: Unauthenticated user initiated Buffer Overflow Vulnerability in User-ID™ Authentication Portal

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.

Source published: 6 May 2026 18:57:39 UTC
Source modified: 15 Oct 2026 01:11:55 UTC
Observed here: 23 Oct 2026 15:48:27 UTC
Source terms: CVE Program Terms of Use

Original source record · Cite this exact observation · Complete original publisher JSON

This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: cve-program · CVE Program Terms of Use. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS 4.0 · 9.3 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

CVSS 4.0 · 8.7 CVSS:4.0/AV:A/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