Live Exposure Defense: From CVE to Confirmed Exposure in 12 Hours – See more

Back
New CVE Detected

CVE-2023-54391 – Authentication Bypass / RCE Precursor – Proxmox Virtual Environment 7.0–8.0 (libpve

Be the first to know when new zero-days emerge:

Subscribe to Email Alerts
Subscribe to RSS Feed

Summary

CVE-2023-54391 is a critical authentication bypass vulnerability in Proxmox Virtual Environment (VE), caused by improper validation of the tfa-challenge parameter in libpve-access-control. The flaw allows an unauthenticated network attacker to log in as any existing, enabled user — including root@pam — who does not have a second authentication factor configured, without supplying any valid credentials.

Technical details

  • Root cause: the API login endpoint accepted a tfa-challenge value without properly verifying that a legitimate second-factor challenge had actually been issued or completed.
  • Trigger condition: the targeted user account must not have two-factor authentication enabled; the attacker submits an arbitrary/forged value in the tfa-challenge parameter when posting to the access ticket (login) API endpoint.
  • Attack vector: network, unauthenticated, low complexity, no user interaction required.
  • Impact: full authentication bypass, allowing an attacker to obtain a valid access ticket for any qualifying account, including privileged accounts, resulting in full compromise of confidentiality, integrity, and availability of the Proxmox VE management interface.

Affected software

  • Proxmox Virtual Environment 7.0 through 7.4
  • Proxmox Virtual Environment 8.0 (initial release)
  • libpve-access-control versions 7.0-7 through 8.0.3

Severity

  • CVSS v3.1 Base Score: 9.8 (Critical) — CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
  • Also scored under CVSS v4.0 as 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

Mitigation and recommended actions

  • Immediate: upgrade libpve-access-control to version 8.0.4 or later, which fixed the issue.
  • Note: all affected Proxmox VE 7.x releases are end of life (since July 2024); organizations still running these versions should plan migration to a supported, patched release in addition to applying the fix.
  • If immediate patching is not possible: restrict network access to the Proxmox VE API/web interface to trusted management networks only, and ensure two-factor authentication is enforced and enabled for all accounts, particularly privileged accounts such as root@pam, as accounts without a configured second factor are the ones exposed by this flaw.

How IONIX identifies potentially affected assets

IONIX matches the following signals against data already collected when it crawled the asset; identifying the technology sends no request beyond that crawl.

  • Page title: Proxmox Virtual Environment, optionally preceded by other text and a dash (e.g. Something - Proxmox Virtual Environment).

References

Are you exposed?

Get a free report of your organization’s exposure to this CVE and threat

  • Mapping of all Assets with this Technology
  • Identification of potentially exposed assets to this CVE
  • Confirmation of verified exploitable assets
Get Exposure Report

How IONIX’s External Exposure Management Platform Detects and Validates
Zero-Days to Shrink MTTR

1

Map your entire attack surface (continously)

IONIX uses multi-factor discovery methods, including DNS analysis, certificate mapping, metadata inspection, and more, to automatically map every internet-facing asset across your environment. This includes cloud instances, third-party platforms, shadow IT, and even forgotten infrastructure that traditional tools miss.

2

Monitor for new CVEs

Dozens of threat intel feeds using agentic technology are continuously analyzed to detect the appearance of proof-of-concept code, exploit kits, and indicators of active targeting. IONIX goes further by applying AI to proactively evaluate whether emerging vulnerabilities are likely to be exploited, even before PoCs go public.

3

Identify Potential External Exposures

Not all CVEs matter. IONIX filters vulnerabilities by asking attacker-centric questions: Can it be reached from the internet? Does it require authentication? Is it being exploited in the wild? This dramatically reduces noise and focuses teams on threats that can actually be weaponized.

4

Create Safe, Scalable Exploit Validations

IONIX transforms real-world PoCs into safe, non-intrusive test payloads that can be run in production environments without disruption. These simulations are precisely targeted to the systems that are vulnerable, ensuring rapid validation without unnecessary load.

5

Execute Exploit Validations

By combining context about software stack, versioning, exposure status, and reachability, IONIX ensures that only the right payloads are executed against the right assets, maximizing efficiency and minimizing risk.

6

Drive Fast and Actionable Remediation

Results are routed through integrations with ticketing, SOAR, and SIEM tools. Issues are written in plain language, bundled into remediation clusters, and prioritized based on asset criticality, exploitability, and blast radius. This shortens mean time to remediation (MTTR) and empowers teams to act with confidence.

Are you exposed?

Get a free report of your organization’s exposure to this CVE and threat

  • Mapping of all Assets with this Technology
  • Identification of potentially exposed assets to this CVE
  • Confirmation of verified exploitable assets
Get Exposure Report
Close

Subscribe to Threat Center RSS

Copy/paste the link below into your preferred RSS reader or follow these instructions to subscribe to Slack alerts.

Open RSS feedSlack setup instructions

Close

Get Real-Time CVE Alerts to Your Email

Be the first to know when new zero-days emerge