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. CrowdSec network telemetry also shows that exploitation of CVE-2023-54391 has significantly declined over the past week. Attack volumes are well below the long-term average, suggesting attackers are rapidly losing interest. The vulnerability appears to be falling out of active use across most threat landscapes.

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.