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Vulnerabilities

Vulnerability · CVE-2023-54391

proxmox virtual_environment Missing Critical Step in Authentication

Published Sep 1, 2026 · catalog updated Sep 1, 2026 · Proxmox Server Solutions GmbH Proxmox Virtual Environment (VE)

Patch now

CVE-2023-54391 is in the CISA known-exploited catalog. Confirm Proxmox Server Solutions GmbH Proxmox Virtual Environment (VE) against the vendor advisory and apply that fix. The CVSS score does not change the priority.

Gaps on this record

  • No version range is stored. A customer cannot check an installed version against this record.
Severity
Unknown—
Known exploitation
CISA KEV and VulnCheck KEV
EPSS
3.06%
Remediation
Remediation guidance
Affected products
vendor Proxmox Server Solutions GmbH Proxmox Virtual Environment (VE)

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. VulnCheck canary evidence. Initial-access exploit intelligence.

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

  • vendor Proxmox Server Solutions GmbH Proxmox Virtual Environment (VE)version unspecified

How to fix CVE-2023-54391

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

CVE-2023-54391 is in the CISA known-exploited catalog. Confirm Proxmox Server Solutions GmbH Proxmox Virtual Environment (VE) against the vendor advisory and apply that fix. The CVSS score does not change the priority.

Which versions are affected?

Affected version ranges are not on this record. Apply remediations or mitigations per vendor instructions or discontinue use of the product if remediation or mitigations are unavailable.

What should an analyst verify?

No weakness class is stored. EPSS 3.06%. The CISA KEV listing is the exploitation evidence. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Code

The project this record applies to. Exploit listings stay in References.

No public source repository is identified for this product.

Timeline

Detection, updates, and resolution for this record.

  1. Sep 1, 2026 · VulnCheck KEV

    Detected

    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 a

  2. Sep 1, 2026 · CISA KEV

    Known exploited

    Apply remediations or mitigations per vendor instructions or discontinue use of the product if remediation or mitigations are unavailable.

Sources

  • CVE.orgVulnerability recordCVE-2023-54391

    Official CVE identifier

    cve.org
  • FIRST EPSSExploitation probabilityCVE-2023-54391

    30-day exploitation probability 3.1%

    first.org
  • VulnCheck KEVConfirmed exploitationCVE-2023-54391

    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 t

    vulncheck.com

References

Freshness

Last verified in this catalog Oct 17, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.