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Vulnerability report

Exploited in the wild High confidence Not in CISA KEV

CVE-2023-54391

Proxmox Virtual Environment (VE) Proxmox VE 7.0 8.0 Authentication Bypass

Proxmox Server Solutions / Proxmox Virtual Environment (VE) · 7.0 to <= 7.4

View live feed Monitor via API Watch CVE-2023-54391
Severity
CVSS 9.3 · Critical
Confidence
High
Exploit status
Exploited in the wild
EPSS
—
First observed
—
Last observed
—

Decision summary

What security teams need to know first

Direct answers before the deeper technical record.

What it is

CVE-2023-54391 is an unauthenticated vulnerability affecting Proxmox Server Solutions Proxmox Virtual Environment (VE). Proxmox Virtual Environment (VE) 7.0 through 8.0 contains an authentication bypass vulnerability...

Is it exploited?

Yes. Previdian tracks this CVE as a known exploited vulnerability. Confidence is high. Also confirmed by third-party sources.

Who is affected?

Proxmox Server Solutions / Proxmox Virtual Environment (VE) 7.0 to <= 7.4.

What should we do?

Prioritize remediation. Validate affected assets and apply vendor fixes on an accelerated timeline.

Overview

Proxmox Virtual Environment (VE) Proxmox VE 7.0 8.0 Authentication Bypass

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.

Vendor Product Affected Status
Proxmox Server Solutions GmbH Proxmox Virtual Environment (VE) Through 7.4 Affected
Proxmox Server Solutions GmbH Proxmox Virtual Environment (VE) 8.0 Affected
View vendor advisory (opens in new tab)
Published
01 Sep 2026
Exploitation Reported
01 Sep 2026
Attack vector
Remote
Complexity
Low
Privileges
None
User interaction
None

Tags

linux

CVE References

  • CVE Record CVE.org · CVE Record https://www.cve.org/CVERecord?id=CVE-2023-54391
  • Vendor Advisory forum.proxmox.com · Vendor Advisory https://forum.proxmox.com/threads/proxmox-virtual-environment-securit...
  • Patch Commit git.proxmox.com · Patch https://git.proxmox.com/?p=pve-access-control.git;a=commit;h=032e7d6d...
  • Third-Party Advisory — vulncheck.com vulncheck.com · Third-Party Advisory https://www.vulncheck.com/advisories/proxmox-ve-authentication-bypass...

Exploitation evidence

Why Previdian marks this CVE as exploited

Third-party attestation and first-party sensor observation are shown separately so teams can judge the evidence chain.

Exploited in the wild

CVE

Recorded 01 Sep 2026

Independent exploitation attestation added to the Previdian record.

Proof of concept available

Recorded 01 Sep 2026

Public scanner or PoC coverage increases practical exploitability.

Known exploited vulnerability sources

Per-source evidence links for KEV attestations are available through the Previdian Pro API.

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Source Added
Previdian First 2026-09-01 20:57 UTC
CVE 2026-09-01 22:10 UTC

Detection

Operational artifacts and observed signals

Make the evidence actionable in scanner, SOC, and edge-control workflows.

Observed signals

Request targets
0
User-Agents
0

Raw values available in Pro and Enterprise.

Scanner coverage

No scanner integrations recorded yet.

Virtual patch status

No Previdian virtual patch is currently available. Future rules ship for ModSecurity, Cloudflare, and AWS WAF.

Learn about virtual patches →

No detection artifacts or sensor request patterns are available for this CVE yet.

Check back as sensor telemetry and scanner integrations are updated.

Risk and context

Severity, weaknesses, and research context

CVSS v4.0

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

EPSS

—

Weaknesses

Missing Critical Step in Authentication CWE-304

All CVSS Scores

CVSS v4.0 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

CVSS v3.1 9.8 Critical

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Potential Proof of Concepts

These PoCs are unverified and could contain malware. Use at your own risk.

PVE 7.4 auth-bypass @NebuSec

public · Created 2026-09-01 11:04:00 UTC

Timeline

From disclosure to observed exploitation

  1. KEV confirmed by CVE

    Exploitation attested by an external source

  2. CVE published

    Vulnerability disclosed publicly

  3. CVE ID reserved

    Identifier reserved by the CNA

  4. Added to Previdian KEV Feed

    High-confidence, third-party attested exploitation

  5. Public PoC available

    Public proof-of-concept code published

Pro API

Automate this intelligence

Confidence, exploit status, sensor telemetry, PoCs, scanner integrations, mentions, and tags are available programmatically for VM, SOC, and CTI workflows.

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  • Evidence confidence and provenance
  • First-party sensor telemetry
  • PoC and scanner references
  • Affected versions and enrichment
  • Automation-ready JSON delivery

GET /api/v2/pro/kevs/CVE-2023-54391

Free JSON includes basic KEV fields 
{
  "cve_id": "CVE-2023-54391",
  "confidence": "High",
  "cvss_score": 9.3,
  "cvss_estimated": false,
  "epss_score": null,
  "exploit_status": {
    "exploited_in_the_wild": true,
    "active_exploitation_observed": false
  },
  "sensor_telemetry": { "attempts": 0, "sensors": 0 }
}