PAN-OS Out-of-Bounds Write Enabling Code Execution Affects Both Palo Alto Networks Firewalls and Siemens RUGGEDCOM APE1808 Industrial Appliances; CISA's May 9th KEV Window Has Closed

Last refreshed2026-09-27

Status: KEV | Advisory ID: CVE-2026-0300

Key Details

CVE	CVE-2026-0300
Vulnerability Name	Palo Alto Networks PAN-OS Out-of-bounds Write Vulnerability
Affected products	Siemens RUGGEDCOM APE1808 Firmware and Palo Alto Networks PAN-OS
Exploitation status	Listed in CISA's Known Exploited Vulnerabilities (KEV) catalog, indicating confirmed active exploitation.
Classified as	CWE-787 (Out-of-bounds Write)
KEV listing	Added to CISA's Known Exploited Vulnerabilities (KEV) catalog on 2026-05-06.
Exploitation prediction (EPSS)	31.72% probability of exploitation in the next 30 days (98% percentile) -- FIRST.org's EPSS model.
Federal remediation deadline	2026-05-09 (CISA KEV, Binding Operational Directive).

Affected Products, Subsystems & Sectors

Vendor	Product	Affected Versions	Patch Status
Siemens	RUGGEDCOM APE1808 Firmware
Palo Alto Networks	PAN-OS

Vendor

Product

Affected Versions

Patch Status

Siemens

RUGGEDCOM APE1808 Firmware

Palo Alto Networks

PAN-OS

Subsystems	PLC/PAC/RTU
Sectors	Critical Manufacturing, Energy, Food and Agriculture, Multi-sector, Transportation Systems

What to Know

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.

What to Do

Monitor Siemens's and Palo Alto Networks's web pages for any future patch releases.

References

Source	Reference
NVD	https://nvd.nist.gov/vuln/detail/CVE-2026-0300
CVE	https://www.cve.org/CVERecord?id=CVE-2026-0300

Source

Reference

NVD

https://nvd.nist.gov/vuln/detail/CVE-2026-0300

CVE

https://www.cve.org/CVERecord?id=CVE-2026-0300

KEV Required Action

Field	Value
KEV Link	https://www.cisa.gov/known-exploited-vulnerabilities-catalog
Date Added to KEV	2026-05-06
Required Action Due Date	2026-05-09
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.

Field

Value

KEV Link

https://www.cisa.gov/known-exploited-vulnerabilities-catalog

Date Added to KEV

2026-05-06

Required Action Due Date

2026-05-09

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.