Exploited vulnerabilities / CVE-2026-0300
Confirmed exploited · remote code execution · Palo Alto Networks PAN-OSCVE-2026-0300
Palo Alto Networks PAN-OS remote code execution, confirmed exploited in the wild.
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.
| CISA's name for it | Palo Alto Networks PAN-OS Out-of-bounds Write Vulnerability |
|---|---|
| Vendor and product | Palo Alto Networks · PAN-OS |
| Type | remote code execution · CWE-787 |
| Exploited | Confirmed by CISA listed 6 May 2026 |
| Likelihood | one of the most likely to be exploited of every vulnerability tracked |
| Deadline | 9 May 2026 · already passed |
| Used in ransomware | Not reported |
| Advisories | security.paloaltonetworks.com ↗ · nvd.nist.gov ↗ |
Three steps, in this order
Patch to the fixed version the vendor names, today if the product faces the internet.
Until it is patched, take the affected service off the internet or put it behind a VPN or allow-list.
Look for signs it was already used: new accounts, web shells, unexpected processes and outbound connections since the date it was listed.
| CISA's 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. |
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Know before someone else finds it
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CVE-2026-0300 in short
Is CVE-2026-0300 being exploited?
Yes. CISA added CVE-2026-0300 to its Known Exploited Vulnerabilities catalogue on 6 May 2026, which it does only on evidence of exploitation in the wild.
What is the CISA deadline for CVE-2026-0300?
US federal agencies must remediate it by 9 May 2026. Everyone else should treat that date as the latest safe point to patch an internet-facing system.
How likely is CVE-2026-0300 to be exploited in the next 30 days?
FIRST's Exploit Prediction Scoring System gives it 42%, the 98th percentile of every CVE it scores.
How do I fix CVE-2026-0300?
Patch to the fixed version the vendor names, today if the product faces the internet. Until it is patched, take the affected service off the internet or put it behind a VPN or allow-list. Look for signs it was already used: new accounts, web shells, unexpected processes and outbound connections since the date it was listed.
Other Palo Alto Networks vulnerabilities being exploited
| CVE | Product | Type | Listed |
|---|---|---|---|
| CVE-2026-0322 | PAN-OS | remote code execution | 14 October 2026 |
| CVE-2026-0257 | PAN-OS | authentication bypass | 29 May 2026 |
Sources: CISA Known Exploited Vulnerabilities catalogue (released 10 November 2026) and FIRST EPSS. Page compiled automatically by SAK T.L.M, the threat-intelligence tool of SAK T.E.C, on 13 November 2026.