CVE-2020-2040: PAN-OS: Buffer overflow when Captive Portal or Multi-Factor Authentication (MFA) is enabled

Severity: critical (CVSS 9.8 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 3.9% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2020-09-09 · updated 2026-06-17
Weakness: CWE-120

Description

A buffer overflow vulnerability in PAN-OS allows an unauthenticated attacker to disrupt system processes and potentially execute arbitrary code with root privileges by sending a malicious request to the Captive Portal or Multi-Factor Authentication interface. This issue impacts: All versions of PAN-OS 8.0; PAN-OS 8.1 versions earlier than PAN-OS 8.1.15; PAN-OS 9.0 versions earlier than PAN-OS 9.0.9; PAN-OS 9.1 versions earlier than PAN-OS 9.1.3.

Affected products

Palo Alto Networks PAN-OS: from 8.0.0 through 8.0.20; from 8.1.0 before 8.1.15; from 9.0.0 before 9.0.9; from 9.1.0 before 9.1.3 — fixed in 8.1.15, 9.0.9, 9.1.3
Palo Alto Networks PAN-OS: from 9.0 before 9.0.9; from 9.1 before 9.1.3; from 8.1 before 8.1.15; 8.0.* — fixed in 9.0.9, 9.1.3, 8.1.15

How to fix

Upgrade to a fixed version: Palo Alto Networks PAN-OS 8.1.15, 9.0.9, 9.1.3; Palo Alto Networks PAN-OS 9.0.9, 9.1.3, 8.1.15. Check the vendor advisory for mitigations.

References

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