CVE-2023-54391 (GCVE-0-2023-54391)
Vulnerability from cvelistv5 – Published: 2026-09-01 21:59 – Updated: 2026-09-03 14:28 Unsupported When Assigned X_Known Exploited VulnerabilityTitle
Proxmox VE 7.0-8.0 Authentication Bypass via tfa-challenge Parameter
Summary
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.
Severity
9.8 (Critical)
SSVC
Exploitation: none
Automatable: yes
Technical Impact: total
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-09-02 11:55 UTC
CWE
- CWE-304 - Missing Critical Step in Authentication
Assigner
References
4 references
| URL | Tags |
|---|---|
| https://forum.proxmox.com/threads/proxmox-virtual… | vendor-advisory |
| https://git.proxmox.com/?p=pve-access-control.git… | patch |
| https://git.proxmox.com/?p=pve-access-control.git… | |
| https://www.vulncheck.com/advisories/proxmox-ve-a… | third-party-advisory |
Impacted products
1 product
| Vendor | Product | Version | CPE status | |
|---|---|---|---|---|
| Proxmox Server Solutions GmbH | Proxmox Virtual Environment (VE) |
Affected:
7.0 , ≤ 7.4
(custom)
Affected: 8.0 (custom) |
guessed |
Date Public
2023-07-14 00:00
Previdian
Known Exploited Vulnerability - GCVE BCP-07 Compliant
KEV entry ID: ce52882c-0d61-41c3-9434-ec6938f4d139
Exploited: Yes
Timestamps
First Seen: 2026-09-01
Asserted: 2026-09-01
Scope
Notes: Proxmox VE 7.0-8.0 Authentication Bypass via tfa-challenge Parameter | Affected: Proxmox Server Solutions / Proxmox Virtual Environment (VE) | CVSS: 9.3 (CRITICAL) | Used in malware: unknown | Not yet in CISA KEV: True
Evidence
Type: Public Report
Signal: Successful Exploitation
Confidence: 70%
Source: previdian
Details
| Feed | Previdian (previdian.com) |
|---|---|
| Title | Proxmox VE 7.0-8.0 Authentication Bypass via tfa-challenge Parameter |
| Vendor | Proxmox Server Solutions |
| Product | Proxmox Virtual Environment (VE) |
| Added Date | 2026-09-01T20:57:00.000Z |
| Cvss Score | 9.3 |
| Epss Score | None |
| Cvss Severity | CRITICAL |
| Epss Percentile | None |
| Used In Malware | unknown |
| Ahead Of Cisa Kev | None |
| Not Yet In Cisa Kev | True |
References
Created: 2026-09-02 21:00 UTC
| Updated: 2026-09-02 21:00 UTC
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Experimental. This forecast is provided for visualization only and may change without notice. Do not use it for operational decisions.
Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.
Sightings
| Author | Source | Type | Date | Other |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or observed by the user.
- Confirmed: The vulnerability has been validated from an analyst's perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
- Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
- Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
- Not confirmed: The user expressed doubt about the validity of the vulnerability.
- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.
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The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the
vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base
model, served locally by ML-Gateway.
They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.
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