Threats / Palo Alto Networks / CVE-2026-0300
CVE-2026-0300
· EUVD no mirror located
· GCVE no mirror located
Verified 2026-08-04
Palo Alto Networks PAN-OS vulnerability
Palo Alto Networks PAN-OS contains an out-of-bounds write vulnerability in the Captive Portal service allowing unauthenticated attackers to execute arbitrary code with root privileges on PA-Series and VM-Series firewalls.
Verdict
Today item — known-exploited.
An unauthenticated remote attacker can exploit a memory corruption flaw in the User-ID Authentication Portal to achieve code execution at the highest privilege level, potentially compromising firewall integrity and all protected network traffic.
CISA KEV Yes · 2026-05-065EPSS 0.32074 (verify live)6CVSS 9.33CISA SSVC Exploitation: active · Automatable: yes · Impact: total4
01
Is it exploitable?
— the evidence, ranked above the scoreReported exploitation
7 independent public reports of in-the-wild exploitation are cataloged.Distinct reporting sources (vendor, incident response, government); open them for the underlying claims.
Exploited in the wild
Listed in the CISA Known Exploited Vulnerabilities catalog (added 2026-05-06).
Probability (EPSS)
EPSS 0.32074 — modeled likelihood of exploitation activity.EPSS is a daily-changing model output — open the source for today's value.
Severity / affected
CVSS 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) · Affected: Palo Alto Networks, PAN-OS. Confirm exact fixed builds in the vendor advisory.CVSS — CNA-assigned (CVE.org), version 4.0, set at disclosure.
Weakness (CWE)
Mapped to CWE-787 Out-of-bounds Write — weakness family: Memory safety.CWE — CNA-assigned (CVE.org); the weakness class drives how the flaw is exploited.
CISA SSVC (triage disposition)
Exploitation: active · Automatable: yes · Technical Impact: totalCISA's own stakeholder-specific triage inputs, published in the CVE record (CISA Coordinator role). NOTE: this is CISA's three decision points; the final Act/Attend/Track decision also requires a Mission & Well-being input not published here, so no overall decision is asserted.
Currency of the record
CISA added this to its KEV catalog the same day the CVE record was published.KEV lag = CISA-KEV dateAdded − CVE.org datePublished; a floor on how long the known-exploited flaw sat in the public record before the federal catalog listed it. Severity/weakness here is CNA- or CISA-assigned (current at disclosure), independent of NVD's analysis backlog.
02
Who’s exploiting it?
— attribution turns risk into urgencyAttribution not established
No confirmed (advisory-backed) threat-actor attribution is established for this record. Absence of a named actor is not absence of compromise — see Coverage & confidence.
03
Why it matters
— the attack path, told twice: adversary, then board1
Front door — unauthenticated access narrative 1
Attacker
I craft malicious packets targeting the Captive Portal service without requiring authentication credentials.
Business
The firewall's perimeter defense is bypassed, eliminating a critical security boundary.
2
Keys to the kingdom — privilege/identity takeover narrative 2
Attacker
I trigger an out-of-bounds write condition that corrupts memory and redirects execution flow to my payload.
Business
Arbitrary code execution at root level grants complete control over firewall operations and configuration.
3
Lateral reach — past segmentation narrative 3
Attacker
I establish persistent access or exfiltrate sensitive firewall data and network traffic logs.
Business
Confidentiality and integrity of all network communications passing through the firewall are compromised.
04
What to do
— defensible action- Remediate per the vendor advisory — confirm the fixed build for your version and verify exposure.1
Say it to the boardA vulnerability with this evidence profile is a defensible budget line, not a backlog ticket — fund the change against the proof above.
05