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Fencer Vulns
critical 9.8

CVE-2026-0300 kev in the critical feed json

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

published 2026-05-06 6 mo ago modified 2026-10-26 13 d ago also EUVD-2026-27879

cvss
9.8
version 3.1, NVD
cisa kev
Exploited
added 2026-05-06
epss
41.7%
EPSS 41.7% chance of exploitation in 30 days, percentile 98%
public exploits
0
none known

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 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.

Patch / fix

cisa required action 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.

  • Palo Alto Networks PAN-OS 10.2.7-h34, 10.2.10-h36, 10.2.13-h21, 10.2.16-h7, 10.2.18-h6, 11.1.4-h33, 11.1.6-h32, 11.1.7-h6, 11.1.10-h25, 11.1.13-h5, 11.1.15, 11.2.4-h17, 11.2.7-h13, 11.2.10-h6, 11.2.12, 12.1.4-h5, 12.1.7

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

cisa ICSA-26-139-02 updated cvss 10.0

Siemens RUGGEDCOM APE1808 Devices

  • Siemens RUGGEDCOM APE1808
    affected: vendor fix, mitigation

Facts from CISA's republication of the vendor's own advisory (CSAF); the linked advisory is the authoritative source. CISA notification · csaf

Timeline

  1. CISA SSVC: exploitation active
  2. Added to CISA KEV
  3. Published
  4. CISA patch deadline

Known exploited

Added
6 mo ago
Patch by
2026-05-09 (6 mo ago)
Ransomware
Not known
Required action
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.
Vendor, product
Palo Alto Networks, PAN-OS
CISA name
Palo Alto Networks PAN-OS Out-of-bounds Write Vulnerability

CISA SSVC

Exploitation
Active, exploited in the wild
Automatable
yes
Technical impact
total
Assessed
6 mo ago

Exploit prediction

41.71% chance of exploitation in the next 30 days, higher than 98% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 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
CNA 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
CNA 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/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
NVD 3.1 9.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Affected products

  • Palo Alto Networks Cloud NGFW
  • Palo Alto Networks PAN-OS
  • Palo Alto Networks Prisma Access
  • Siemens RUGGEDCOM APE1808

Classification

Weakness
Technology feeds

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.