Skip to content
vulnerability

CVE-2026-0300

9.8
Critical
KEV · Exploited in wildEPSS 42%Patch available

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.

exploited
Yes, in CISA KEV since 6 May 2026fix by 9 May 2026 (CISA deadline for US federal agencies)unvetted proof-of-concept code on github
fix
Patch available see the advisory in the references
likelihood
EPSS 41.7%
Published 6 May 2026Analysed here 2 Nov 2026

do firstApply 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.

triage
server-sideruntimeWAF can block: noAV · networkCWE-787· Out-of-Bounds Write

Can a WAF block it? No. The vulnerability is triggered by specially crafted packets sent to the User-ID Authentication Portal service, which is not described as HTTP-based. Therefore, the attack does not use HTTP requests and cannot be filtered by a web application firewall.

Also consider: patch

Based on an AI reading of the CVE description, and no vendor rule found yet. We check Cloudflare, AWS, Google Cloud Armor and Azure; for Akamai, Imperva, Fastly, F5, ask your vendor.

cvss vector
attack vectornetworkattack complexitylowprivileges requirednoneuser interactionnonescopeunchangedconfidentialityhighintegrityhighavailabilityhigh
CVSS 3.1 · CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
common questions

Is CVE-2026-0300 being exploited?

Yes. CVE-2026-0300 appears in CISA's Known Exploited Vulnerabilities catalog, which means exploitation in the wild has been confirmed and reported. Treat it as active rather than theoretical, and patch it ahead of higher-scoring vulnerabilities that carry no exploitation evidence.

How severe is CVE-2026-0300?

CVE-2026-0300 is rated Critical with a CVSS score of 9.8. Severity describes how bad exploitation would be, not how likely it is: pair it with exploitation evidence before deciding what to patch first.

Is there a patch for CVE-2026-0300?

Yes. A fix has been recorded for CVE-2026-0300. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.

What does CVE-2026-0300 affect?

CVE-2026-0300 affects paloaltonetworks:pan-os, siemens:ruggedcom_ape1808_firmware. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.

Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.

executive summary
technical analysis
affected
paloaltonetworks:pan-ossiemens:ruggedcom_ape1808_firmware
affected versions
Palo Alto Networks PAN-OS
  • affected>= 12.1.0 and < 12.1.7
  • affected>= 11.2.0 and < 11.2.12
  • affected>= 11.1.0 and < 11.1.15
  • affected>= 10.2.0 and < 10.2.18-h6

As published in the CVE Program record. A version outside these ranges is not a statement that it is unaffected — vendors sometimes understate a range, and distribution-backported builds carry upstream numbers that do not reflect what was patched into them.

public exploits

Unvetted proof-of-concept code on GitHub: 10 GitHub proofs of concept

Listed so you can judge urgency, not as a recommendation to run anything. GitHub “proofs of concept” are unvetted: some are fake or carry malware. Exploit-DB marks the entries its staff verified.

cisa ssvc

exploitation
active
automatable
yes
technical impact
total

Assessed by CISA 6 May 2026 (SSVC 2.0.3).

timeline

  1. 6 May 2026Added to CISA KEV (exploited in the wild)
  2. 6 May 2026First proof-of-concept repository on GitHub (unvetted) · same day later
  3. 6 May 2026CISA SSVC assessment: exploitation active · same day later
  4. 6 May 2026Published · 1 day later
  5. 9 May 2026CISA remediation due date (US federal agencies) · 2 days later
  6. 15 Oct 2026CVE record last updated · 159 days (about 5 months) later
  7. 2 Nov 2026Analysed by vulneraibility.com · 19 days later
how to fix
Remediation steps are tailored for users whose stack is affected. Add this technology to your stack to see the fix checklist.
references
NVDCVE.orgCVE DetailsSource
3 references in the CVE record: 1 advisory, 2 links

sources

  • CVE List (CVE.org): description, affected versions, references; CVE Terms of Use
  • NVD: CVSS and CPE data
  • CISA KEV catalog: exploitation, date added, due date
  • CISA Vulnrichment (ADP): SSVC decision points
  • FIRST EPSS: exploit probability and percentile
  • PoC-in-GitHub: GitHub repositories that claim a proof of concept
  • Summary, impact and triage tags: written by our AI analysis pipeline from the sources above. Check them against the sources.
get alerted

Track only the vulnerabilities that affect your infrastructure.

start for free

© 2026 vulneraibility.com, all rights reserved