CVE-2023-54391
Proxmox VE 7.0-8.0 Authentication Bypass via tfa-challenge Parameter
CRITICAL 9.3EPSS 3.1%
Proxmox Virtual Environment (VE) 7.0 through 8.0 contains an authentication bypass vulnerability in libpve-access-control before 8.0.4 that allows unauthenticated attackers to authenticate as any existing enabled user without a configured second factor by supplying an arbitrary tfa-challenge value in the API login endpoint. Attackers can send a POST request to the access ticket API endpoint with any value in the tfa-challenge parameter to completely skip password verification, gaining unauthorized access including to the root@pam account. All affected releases are end of life.
- Affected
- Proxmox Server Solutions GmbH · Proxmox Virtual Environment (VE)
- CVSS v4.0 VULNCHECK
- 9.3 CRITICAL
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X - CVSS v3.1 VULNCHECK
- 9.8 CRITICAL
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H - EPSS
- 3.06% chance of exploitation in the next 30 days, 87th percentile
- Nuclei
- critical
- Published
- 2026-09-01
- Updated
- 2026-10-01
Proof-of-concept exploits (3)
- alexandrov666/CVE-2023-54391-RCE2★ · 2026-10-08
- alexand0www/CVE-2023-54391-RCE2★ · 2026-10-08
- Lewis1766/CVE-2023-54391-POC0★ · 2026-10-19