Vulnerability report

Exploited in the wild Confirmed confidence In CISA KEV

CVE-2026-0300

Cloud NGFW

Palo Alto Networks / Cloud NGFW · affected before *

Watch CVE-2026-0300 Browse KEV feed
Severity
CVSS 9.3 · Critical
Confidence
Confirmed
Exploit status
Exploited in the wild
EPSS
31.7%
First observed
—
Last observed
—

Decision summary

What security teams need to know first

Direct answers before the deeper technical record.

What it is

CVE-2026-0300 is an unauthenticated vulnerability affecting Palo Alto Networks Cloud NGFW and 2 other products. A buffer overflow vulnerability in the User-ID™ Authentication Portal (aka Captive Portal) service of...

Is it exploited?

Yes. Previdian tracks this CVE as a known exploited vulnerability. Confidence is confirmed. Listed in CISA KEV. Also confirmed by third-party sources.

Who is affected?

Palo Alto Networks / Cloud NGFW affected before *.

What should we do?

Prioritize remediation. Validate affected assets and apply vendor fixes on an accelerated timeline.

Overview

Cloud NGFW

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.

Siemens Affected
RUGGEDCOM APE1808
Before *
Palo Alto Networks Unaffected
Cloud NGFW
All
Palo Alto Networks Affected
PAN-OS
Before 12.1.7 Before 11.2.12 Before 11.1.15 Before 10.2.18-h6
Palo Alto Networks Unaffected
Prisma Access
All
View vendor advisory (opens in new tab)
Published
06 May 2026
Exploitation Reported
01 Jun 2026
Attack vector
Remote
Complexity
Low
Privileges
None
User interaction
None

Tags

cisa edge

CVE References

Exploitation evidence

Why Previdian marks this CVE as exploited

Third-party attestation and first-party sensor observation are shown separately so teams can judge the evidence chain.

Exploited in the wild

CVE

Recorded 01 Jun 2026

A trusted third party reported exploitation.

Proof of concept available

GitHub

Recorded 21 May 2026

Public scanner or PoC coverage increases practical exploitability.

Known exploited vulnerability sources

Per-source evidence links for KEV attestations are available through the Previdian Pro API.

Learn about Pro API access
Source Added
CVE First 2026-06-01 13:26 UTC
CISA 2026-06-02 14:01 UTC

Detection

Operational artifacts and observed signals

Make the evidence actionable in scanner, SOC, and edge-control workflows.

Observed signals

Request targets
User-Agents
Callback hosts
0
0
0

Request targets and User-Agents available in Pro. Callback host details available in Enterprise.

Scanner coverage

No scanner integrations recorded yet.

Virtual patch status

No Previdian virtual patch is currently available. Future rules ship for ModSecurity, Cloudflare, and AWS WAF.

Learn about virtual patches →

No detection artifacts or sensor request patterns are available for this CVE yet.

Check back as sensor telemetry and scanner integrations are updated.

Risk and context

Severity, weaknesses, and research context

CVSS v4.0

9.3 Critical

Potential damage if exploited. Separate from whether attackers are using it.

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

EPSS

31.7%

Estimated chance of exploitation in the next 30 days. Previdian's warning comes from evidence, not this score.

Weaknesses

Out-of-bounds Write CWE-787

Recent mention · RecordedFuture

August 2026 CVE Landscape

In August 2026, Insikt Group® identified 73 high-impact vulnerabilities that should be prioritized for remediation, 43 of which had a Very Critical Recorded Future Risk Score. This represents a 14% decrease from last month.

Read full advisory

All CVSS Scores

CVSS v4.0 9.3 Critical

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

CVSS v3.1 9.8 Critical

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

All Mentions

Recent mention · RecordedFuture

August 2026 CVE Landscape

RecordedFuture · 08 Sep 2026

In August 2026, Insikt Group® identified 73 high-impact vulnerabilities that should be prioritized for remediation, 43 of which had a Very Critical Recorded Future Risk Score. This represents a 14% decrease from last month.

Recent mention · Tenable Blog

The Agentic AI threat cluster: Seven incidents, three actors, and what they mean for your exposure

Tenable Blog · 15 Aug 2026

Tenable’s Research Special Operations (RSO) team has been tracking a cluster of agentic AI threat activity since late July 2026. The Taiwan autonomous AI cyber attack confirmed what the cluster data already showed: near-autonomous offensive AI has crossed from theoretical risk to operational reality.Key TakeawaysTaiwan's Ministry of Digital Affairs confirmed a near-autonomous AI cyber attack in July 2026 in which autonomous agents mapped 21 connected government systems, compromised 85 accounts, and exfiltrated more than 2,564 personnel records in approximately four days.The Taiwan campaign...

Recent mention · Palo Alto Networks Security Advisories

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

Palo Alto Networks Security Advisories · 28 May 2026

Potential Proof of Concepts

These PoCs are unverified and could contain malware. Use at your own risk.

sam00/POC-CVE-2026-0300-exploit

github · Created 2026-08-06 12:37:02 UTC · 0 stars · AI assessment 90%

Palo Alto - CVE-2026-0300 exploit

Timeline

From disclosure to observed exploitation

  1. 12:37 UTC

    Public PoC available

    Public proof-of-concept code published

  2. 14:01 UTC

    Added to CISA KEV

    Listed in the CISA Known Exploited Vulnerabilities catalog

  3. 13:26 UTC

    Added to Previdian KEV Feed

    High-confidence, third-party attested exploitation

  4. 18:57 UTC

    CVE published

    Vulnerability disclosed publicly

  5. 20:44 UTC

    CVE ID reserved

    Identifier reserved by the CNA

Pro API

Automate this intelligence

Confidence, exploit status, sensor telemetry, PoCs, scanner integrations, mentions, and tags are available programmatically for VM, SOC, and CTI workflows.

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  • Evidence confidence and provenance
  • First-party sensor telemetry
  • PoC and scanner references
  • Affected versions and enrichment
  • Automation-ready JSON delivery

GET /api/v2/pro/kevs/CVE-2026-0300

Free JSON includes basic KEV fields 
{
  "cve_id": "CVE-2026-0300",
  "confidence": "Confirmed",
  "cvss_score": 9.3,
  "cvss_estimated": false,
  "epss_score": 0.31725,
  "exploit_status": {
    "exploited_in_the_wild": true,
    "active_exploitation_observed": false
  },
  "sensor_telemetry": { "attempts": 0, "sensors": 0 }
}