CVE-2026-0300: Palo Alto Networks PAN-OS Out-of-bounds Write Vulnerability

Patch now

CRITICAL 9.8EXPLOITEDREMOTEMITIGATEMITIGATE

CVE-2026-0300 is a critical-severity flaw (CVSS 9.8) affecting pan-os, ruggedcom ape1808 firmware, reported as exploited in the wild. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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://knowled

Why this priority

Critical severity
EPSS top 1%: very likely to be exploited
Exploited in the wild (CISA KEV)
CISA SSVC: automatable with total technical impact
Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	9.8 (Critical)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	41.7% (top 1%)
CISA exploited list	Yes, fix due 2026-05-09
Weakness	CWE-787
Published	2026-05-06
Last modified	2026-10-26

Publisher (CNA): Palo Alto Networks, Inc. · Vendor: paloaltonetworks · siemens

Last updated 2026-10-26 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-05-06Exploited Added to the CISA Known Exploited Vulnerabilities list
2026-05-06 19:16 UTCPublished CVE record published
2026-05-09Deadline CISA due date for US federal agencies to patch
2026-10-26 19:10 UTCUpdated Record last modified

paloaltonetworks pan-os MITIGATE

Affected: 10.2.0 · 10.2.1 · 10.2.2 · 10.2.3 · 10.2.4 · 10.2.5 · 10.2.6 · 10.2.7

Fixed in: no fixed release known

Safe to downgrade to: a release before 10.2.0

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

siemens ruggedcom ape1808 firmware MITIGATE

Affected: all versions

Fixed in: no fixed release known

Safe to downgrade to: no unaffected older release

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

Exact fixes by distribution

A distro patch exists: prefer upgrading over downgrading.

Fedora 46 · ddnet · FIXED · 20.2-1.fc46 · FEDORA-2026-6991b4ab14 · source

sudo dnf upgrade --advisory=FEDORA-2026-6991b4ab14

Fedora ELN · libplacebo · FIXED · 7.360.1-5.eln159 · FEDORA-2026-92226f221e · source

sudo dnf upgrade --advisory=FEDORA-2026-92226f221e

Public exploits and detection

Public code exists for this CVE. Treat unpatched systems as at risk, and only run PoCs in a lab.

GitHub PoC: p3Nt3st3r-sTAr/CVE-2026-0300-POC (22 stars)
GitHub PoC: matad0r-maghribi/CVE-2026-0300-PANOS (4 stars)
GitHub PoC: qassam-315/PAN-OS-User-ID-Buffer-Overflow-PoC (3 stars)

Advisories and coverage

Official advisories

IPA Japan Security Alerts: Palo Alto Networks製PAN-OSの脆弱性対策について(CVE-2026-0300) 2026-05-07

Research and news

Wiz Research: Critical Buffer Overflow Vulnerability in PAN-OS Exploited in-the-Wild 2026-05-06

Verify at the official source NVD · CVE Program · CISA KEV catalog · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-0300?

pan-os: mitigate or apply the listed mitigation; ruggedcom ape1808 firmware: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2026-0300 being exploited?

Yes. CVE-2026-0300 is on the CISA Known Exploited Vulnerabilities list, so treat it as patch-now.

What does CVE-2026-0300 affect?

CVE-2026-0300 affects pan-os, ruggedcom ape1808 firmware. Severity is critical (CVSS 9.8). 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

How urgent is CVE-2026-0300?

Priority 92/100. Critical severity; EPSS top 1%: very likely to be exploited; Exploited in the wild (CISA KEV); CISA SSVC: automatable with total technical impact; Remotely exploitable, no login, no user action

Software pages

Palo Alto PAN-OS vulnerabilities · Siemens vulnerabilities

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References

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