PAN-OS Buffer overflow vulnerability (CVE-2020-2040)

Within a span of three months, one more critical vulnerability with a score of 10.0 has been observed in PAN-OS devices. When a Captive Portal or Multi-factor authentication interface is enabled on PAN-OS devices, it is considered to be vulnerable to critical buffer overflow vulnerability. This vulnerability is classified as CWE-120 and assigned CVE-2020-2040, on Sept 9, 2020.

This vulnerability disturbs the cadence of PAN-OS devices primarily because of two factors. Firstly, it doesn’t require any authentication, and secondly, it has a potential to disrupt system processes and execute arbitrary code injection. Once exploited, an unauthenticated user can gain root privileges by sending a malicious request to the PAN-OS Captive Portal or the  Multi-Factor Authentication (MFA) interface. This issue is applicable only where either Captive Portal is enabled or MFA  is configured as per the steps mentioned in the Configure Multi-Factor Authentication section of the PAN-OS® Administrator’s Guide.

So far, there has been no information of this CVE being exploited in the wild, and more than ~5k PAN-OS devices are active at the time when this blog was published.

Image Source: Shodan

Affected Products

Image Source: Palo Alto



Users are advised to update their PAN-OS installations to PAN-OS 8.1.15, PAN-OS 9.0.9, PAN-OS 9.1.3, and all later PAN-OS versions. For information, refer to the following article:

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


Qualys customers can scan their network with QID 13975 to detect vulnerable assets.

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