Proxmox Virtual Environment (VE) - Authentication Bypass (CVE-2023-54391)

CVE-2023-54391 is a critical authentication bypass vulnerability in Proxmox Virtual Environment (VE) versions 7.0 through 8.0, affecting libpve-access-control before 8.0.4. Unauthenticated remote attackers can bypass password verification by submitting an arbitrary two-factor authentication challenge, potentially authenticating as enabled users—including root@pam—and gaining complete control of the virtualization environment.

CrowdSec has been tracking this vulnerability and its exploits since 4th of September 2026.

CrowdSec network data shows that most actors exploiting CVE-2023-54391 rely on broad, untargeted scans with minimal filtering. The activity is largely automated and opportunistic in nature. Telemetry from the CrowdSec network also shows that exploitation activity for CVE-2023-54391 remains steady week-over-week. Attack volumes are consistent with long-term trends, indicating sustained interest from threat actors. CVE-2023-54391 continues to be an active part of the threat landscape and will likely remain this way for the forseeable future.

Attackers target the Proxmox VE authentication endpoint /api2/json/access/ticket with the default root@pam username and password, alongside a crafted tfa-challenge parameter to bypass two-factor authentication and obtain a privileged session ticket.