CVE-2023-54391

Proxmox VE 7.0-8.0 Authentication Bypass via tfa-challenge Parameter

Published Sep 1, 2026 CVSS 4.0 · 9.3 Critical EPSS 3.0% KEV · Not listed
Description
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.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

No advisories available
History
Type Values Removed Values Added
First Time appeared Proxmox virtual Environment
CPEs cpe:2.3:a:proxmox:virtual_environment:*:*:*:*:*:*:*:*
cpe:2.3:a:proxmox:virtual_environment:8.0:*:*:*:*:*:*:*
Vendors & Products Proxmox virtual Environment
Type Values Removed Values Added
First Time appeared Proxmox
Proxmox proxmox Virtual Environment (ve)
Vendors & Products Proxmox
Proxmox proxmox Virtual Environment (ve)
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'none', 'Technical Impact': 'total'}, 'version': '2.0.3'}

Type Values Removed Values Added
Description 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.
Title Proxmox VE 7.0-8.0 Authentication Bypass via tfa-challenge Parameter
Weaknesses CWE-304
References
Metrics cvssV3_1

{'score': 9.8, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H'}

cvssV4_0

{'score': 9.3, 'vector': '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'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
VulnCheck
Published
Updated
Oct 1, 2026, 3:19 PM
Reserved
Sep 1, 2026, 9:23 PM
Status
Deferred
Published
Sep 1, 2026, 10:17 PM
Modified
Sep 8, 2026, 8:18 PM