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CVE-2026-0300

91
FAUCET Score

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.

First published: May 6, 2026Last modified: May 12, 2026

Impacted Technologies

VendorProductVersion(s)CPE
10.2.0CPE matchmatch criteria
cpe:2.3:o:paloaltonetworks:pan-os:10.2.0:*:*:*:*:*:*:*
10.2.1CPE matchmatch criteria
cpe:2.3:o:paloaltonetworks:pan-os:10.2.1:*:*:*:*:*:*:*
10.2.2CPE matchmatch criteria
cpe:2.3:o:paloaltonetworks:pan-os:10.2.2:*:*:*:*:*:*:*
10.2.3CPE matchmatch criteria
cpe:2.3:o:paloaltonetworks:pan-os:10.2.3:*:*:*:*:*:*:*
10.2.4CPE matchmatch criteria
cpe:2.3:o:paloaltonetworks:pan-os:10.2.4:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 4.0

9.3CRITICAL

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/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:Y/R:U/V:C/RE:M/U:Red

Attack Vector
NETWORK
Attack Complexity
LOW
Attack Requirements
NONE
Privileges Required
NONE
User Interaction
NONE
VS Confidentiality
HIGH
VS Integrity
HIGH
VS Availability
HIGH
SS Confidentiality
LOW
SS Integrity
LOW
SS Availability
NONE
Exploit Maturity
ATTACKED
CvssVersion
4.0

Exploit Intelligence

EPSS Score
32.07%
Probability of exploitation in next 30 days
EPSS Percentile
98.1%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
Added to KEV · May 6, 2026
This CVE's current EPSS score of 0.3207 is in the 95th percentile among its peer group of 36,897 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.1 Reddit, 0.3 Bluesky, 0.3 Mastodon, and 2.4 GitHub mentions.

Media Mentions

The average CVE in this peer group has 0.3 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Vendor Patches (1)

paloaltoworkaround availablevia vendor_rss
View patch

Vendor Advisories (1)

paloaltopaloalto:security.paloaltonetworks.com/CVE-2026-0300CRITICAL

CVE-2026-0300 PAN-OS: Unauthenticated user initiated Buffer Overflow Vulnerability in User-ID™ Authentication Portal (Severity: CRITICAL)

May 5, 2026

References

cert-portal.siemens.com / productcert/html/ssa-967325.html
Third Party Advisory
cisa.gov / known-exploited-vulnerabilities-catalog
US Government Resource
security.paloaltonetworks.com / CVE-2026-0300
MitigationVendor Advisory