How severe is CVE-2026-0300?

CVE-2026-0300 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2026-0300 being actively exploited?

Yes. CVE-2026-0300 is on CISA's Known Exploited Vulnerabilities (KEV) catalog, added on 2026-05-06, which means active exploitation has been confirmed. It should be prioritised for remediation.

What products are affected by CVE-2026-0300?

CVE-2026-0300 primarily affects Paloaltonetworks Pan-os. In total, 163 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2026-0300?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Because this CVE is known to be actively exploited, treat remediation as urgent — CISA KEV typically sets a short remediation deadline.

Does CVE-2026-0300 have an EU (EUVD) identifier?

Yes. CVE-2026-0300 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-27879. It is also flagged as exploited in the EUVD (since 2026-05-06).

When was CVE-2026-0300 published?

CVE-2026-0300 was published on 2026-05-06 and last updated on 2026-06-17.

CVE-2026-0300

CVE-2026-0300 is a critical-severity vulnerability in Paloaltonetworks Pan-os with a CVSS 3.x base score of 9.8. It is listed in CISA's Known Exploited Vulnerabilities (KEV) catalog, confirming it has been exploited in the wild (added 2026-05-06). The underlying weakness is classified as CWE-787.

Key facts

Severity: Critical (CVSS 3.x base score 9.8)
CVSS v4: 9.3
EPSS exploit prediction: 36% (98th percentile)
Actively exploited: Yes — listed in CISA KEV (added 2026-05-06)
EU (EUVD) id: EUVD-2026-27879
EU exploitation: Flagged exploited in the ENISA EU Vulnerability Database (since 2026-05-06)
Weakness: CWE-787
Affected product: Paloaltonetworks Pan-os
Published: 2026-05-06
Last modified: 2026-06-17

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.

Frequently asked questions

What is CVE-2026-0300?: 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.
How severe is CVE-2026-0300?: CVE-2026-0300 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2026-0300 being actively exploited?: Yes. CVE-2026-0300 is on CISA's Known Exploited Vulnerabilities (KEV) catalog, added on 2026-05-06, which means active exploitation has been confirmed. It should be prioritised for remediation.
What products are affected by CVE-2026-0300?: CVE-2026-0300 primarily affects Paloaltonetworks Pan-os. In total, 163 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2026-0300?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Because this CVE is known to be actively exploited, treat remediation as urgent — CISA KEV typically sets a short remediation deadline.
Does CVE-2026-0300 have an EU (EUVD) identifier?: Yes. CVE-2026-0300 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-27879. It is also flagged as exploited in the EUVD (since 2026-05-06).
When was CVE-2026-0300 published?: CVE-2026-0300 was published on 2026-05-06 and last updated on 2026-06-17.

References

Affected products (163)

cpe:2.3:o:paloaltonetworks:pan-os:10.2.0:*:*:*:*:*:*:*
cpe:2.3:o:paloaltonetworks:pan-os:10.2.1:*:*:*:*:*:*:*
cpe:2.3:o:paloaltonetworks:pan-os:10.2.2:*:*:*:*:*:*:*
cpe:2.3:o:paloaltonetworks:pan-os:10.2.3:*:*:*:*:*:*:*
cpe:2.3:o:paloaltonetworks:pan-os:10.2.4:*:*:*:*:*:*:*
cpe:2.3:o:paloaltonetworks:pan-os:10.2.5:*:*:*:*:*:*:*
cpe:2.3:o:paloaltonetworks:pan-os:10.2.6:*:*:*:*:*:*:*
cpe:2.3:o:paloaltonetworks:pan-os:10.2.7:-:*:*:*:*:*:*
cpe:2.3:o:paloaltonetworks:pan-os:10.2.7:h1:*:*:*:*:*:*
cpe:2.3:o:paloaltonetworks:pan-os:10.2.7:h12:*:*:*:*:*:*
cpe:2.3:o:paloaltonetworks:pan-os:10.2.7:h16:*:*:*:*:*:*
cpe:2.3:o:paloaltonetworks:pan-os:10.2.7:h19:*:*:*:*:*:*
cpe:2.3:o:paloaltonetworks:pan-os:10.2.7:h21:*:*:*:*:*:*
cpe:2.3:o:paloaltonetworks:pan-os:10.2.7:h24:*:*:*:*:*:*
cpe:2.3:o:paloaltonetworks:pan-os:10.2.7:h3:*:*:*:*:*:*
cpe:2.3:o:paloaltonetworks:pan-os:10.2.7:h32:*:*:*:*:*:*
cpe:2.3:o:paloaltonetworks:pan-os:10.2.7:h6:*:*:*:*:*:*
cpe:2.3:o:paloaltonetworks:pan-os:10.2.7:h8:*:*:*:*:*:*
cpe:2.3:o:paloaltonetworks:pan-os:10.2.8:*:*:*:*:*:*:*
cpe:2.3:o:paloaltonetworks:pan-os:10.2.9:*:*:*:*:*:*:*
cpe:2.3:o:paloaltonetworks:pan-os:10.2.10:-:*:*:*:*:*:*
cpe:2.3:o:paloaltonetworks:pan-os:10.2.10:h10:*:*:*:*:*:*
cpe:2.3:o:paloaltonetworks:pan-os:10.2.10:h12:*:*:*:*:*:*
cpe:2.3:o:paloaltonetworks:pan-os:10.2.10:h14:*:*:*:*:*:*
cpe:2.3:o:paloaltonetworks:pan-os:10.2.10:h17:*:*:*:*:*:*
cpe:2.3:o:paloaltonetworks:pan-os:10.2.10:h18:*:*:*:*:*:*
cpe:2.3:o:paloaltonetworks:pan-os:10.2.10:h2:*:*:*:*:*:*
cpe:2.3:o:paloaltonetworks:pan-os:10.2.10:h21:*:*:*:*:*:*
cpe:2.3:o:paloaltonetworks:pan-os:10.2.10:h27:*:*:*:*:*:*
cpe:2.3:o:paloaltonetworks:pan-os:10.2.10:h3:*:*:*:*:*:*
cpe:2.3:o:paloaltonetworks:pan-os:10.2.10:h30:*:*:*:*:*:*
cpe:2.3:o:paloaltonetworks:pan-os:10.2.10:h31:*:*:*:*:*:*
cpe:2.3:o:paloaltonetworks:pan-os:10.2.10:h4:*:*:*:*:*:*
cpe:2.3:o:paloaltonetworks:pan-os:10.2.10:h5:*:*:*:*:*:*
cpe:2.3:o:paloaltonetworks:pan-os:10.2.10:h7:*:*:*:*:*:*
cpe:2.3:o:paloaltonetworks:pan-os:10.2.10:h9:*:*:*:*:*:*
cpe:2.3:o:paloaltonetworks:pan-os:10.2.11:*:*:*:*:*:*:*
cpe:2.3:o:paloaltonetworks:pan-os:10.2.12:*:*:*:*:*:*:*
cpe:2.3:o:paloaltonetworks:pan-os:10.2.13:-:*:*:*:*:*:*
cpe:2.3:o:paloaltonetworks:pan-os:10.2.13:h1:*:*:*:*:*:*

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