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.
Published: 2026-09-01
Score: 9.3 Critical
EPSS: n/a
KEV: No
Impact: n/a
Action: n/a
AI Analysis

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Remediation

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Tracking

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Advisories

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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'}

Subscriptions

No data.

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
  • CWE-304

    Missing Critical Step in Authentication