Palo Alto Networks PAN-OS Authentication Bypass Vulnerability
CVE-2026-0257 is a security vulnerability in Palo Alto Networks PAN-OS, added to CISA KEV on May 29, 2026. Patch priority: Patch now. Known ransomware use: yes.
What it is
Palo Alto Networks PAN-OS contains an authentication bypass vulnerability that allows attackers to bypass security restrictions and establish an unauthorized VPN connection.
Known to be used in ransomware campaigns. Active threat actors have chained this vulnerability into ransomware operations — treat patching as a same-week priority, not a "next maintenance window" task. The fix is the same one below; the urgency is higher.
Who's affected
Affects anyone behind a Palo Alto firewall or using GlobalProtect VPN. The firewall is the network edge; the VPN is how remote workers reach inside the perimeter — exploitation puts an attacker on the internal network without touching a workstation.
What to do
Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.
If you don't have someone in-house to verify the patch deployed across every endpoint — or you're not sure whether you're affected — that's exactly the kind of triage we do. Book a free 20-minute triage call.
Insurance readiness
Your insurer will ask if this is patched.
Unpatched entries on CISA's Known Exploited Vulnerabilities list are exactly what cyber-insurance carrier questionnaires probe for, and knowing which controls they check is how you keep a renewal from stalling.
Get the free carrier questionnaire →Severity
CVSS base score: 9.1 — CRITICAL
Weakness classification: CWE-565
CISA due date
Federal deadline: June 1, 2026. Federal agencies must complete the required action by this date. For private SMBs the deadline is advisory — but treat it as a strong recommendation, especially if you handle regulated data (HIPAA, GLBA, ABA model rules).
EPSS
EPSS score: 93.9% — higher than 100% of all scored CVEs.
EPSS estimates the probability of exploitation activity in the next 30 days. Every entry on this site is already confirmed exploited, so read it as relative urgency among the things you still have open, not as permission to wait.
Other exploited Palo Alto Networks PAN-OS entries
More CISA KEV entries for Palo Alto Networks PAN-OS. Same product line, same actively-exploited status.
Source
This entry comes from CISA's Known Exploited Vulnerabilities catalog, public US-Government data we pull daily. The plain-language framing and the what-to-do guidance above are ours. View the original entry on cisa.gov.