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.

Attack Vector Network

Attack Complexity Low

Privileges Required None

Attack Requirements None

User Interaction None

Vulnerable System Confidentiality Impact High

Vulnerable System Integrity Impact High

Vulnerable System Availability Impact High

Subsequent System Confidentiality Impact None

Subsequent System Integrity Impact None

Subsequent System Availability Impact None

Attack Vector Network

Attack Complexity Low

Privileges Required None

Scope Unchanged

Confidentiality Impact High

Integrity Impact High

Availability Impact High

User Interaction None

No CVSS v3.0

No CVSS v2

This CVE is not in the KEV list.

No EPSS score available.

Key SSVC decision points have not yet been added.

Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).

Vendor Product Default status Versions
Proxmox Server Solutions GmbH Proxmox Virtual Environment (VE) unaffected
Version Status Constraints
7.0 affected ≤ 7.4
8.0 affected —

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Project Subscriptions

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Advisories

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Fixes

Solution

No solution given by the vendor.

Workaround

No workaround given by the vendor.

References
Link Providers
https://forum.proxmox.com/threads/proxmox-virtual-environment-security-advisories.149331/page-4#post-867929 cve-icon cve-icon
https://git.proxmox.com/?p=pve-access-control.git;a=commit;h=032e7d6d441f89a48cadfd7f47e957c8a561c022 cve-icon cve-icon
https://www.vulncheck.com/advisories/proxmox-ve-authentication-bypass-via-tfa-challenge-parameter cve-icon cve-icon
History

Tue, 01 Sep 2026 22:00:00 +0000

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'}

Projects

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cve-icon MITRE

Status: PUBLISHED

Assigner: VulnCheck

Published:

Updated: 2026-09-01T21:59:53.698Z

Reserved: 2026-09-01T21:23:55.860Z

Link: CVE-2023-54391

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Received

Published: 2026-09-01T22:17:10.283

Modified: 2026-09-01T22:17:10.283

Link: CVE-2023-54391

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-09-01T23:30:05Z

Weaknesses