Proxmox Virtual Environment (VE): Missing Critical Step in Authentication
CVE-2023-54391 is a critical-severity missing critical step in authentication vulnerability in Proxmox Virtual Environment (VE) from Proxmox Server Solutions, with a CVSS 3.1 base score of 9.8 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. Affected Proxmox Virtual Environment (VE) versions: 7.0 through 7.4; 8.0. The record does not name a fixed version, so check the vendor advisory. There is no confirmed exploitation so far. EPSS estimates a 3.02% chance of exploitation within 30 days, higher than 88% of scored CVEs.
Critical severity: a successful attack would have severe impact.
What to do
- Check which version of Proxmox Virtual Environment (VE) you run against the affected versions below, and install the vendor's latest release.
- Read the advisory on forum.proxmox.com for workarounds and exact fixed builds.
- Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Proxmox Server Solutions | Proxmox Virtual Environment (VE) | 7.0 through 7.4; 8.0 | Not stated |
Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.
How the severity score breaks down
- Attack vector
- NetworkCan be exploited remotely over a network, including the internet.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- NoneNo account or login is needed.
- User interaction
- NoneNo action by a victim is required.
- Scope
- UnchangedImpact stays within the vulnerable component.
- Confidentiality
- HighAll data handled by the component can be read.
- Integrity
- HighData or code can be modified at will.
- Availability
- HighThe component can be taken down completely.
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H. Scored by CNA (vulncheck.com).
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 4.0 | 9.3 | Critical | CNA (vulncheck.com) |
| CVSS 3.1 | 9.8 | Critical | CNA (vulncheck.com) |
Official 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.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Missing Critical Step in Authentication
The product implements an authentication technique, but it skips a step that weakens the technique.
More Missing Critical Step in Authentication vulnerabilities (CWE-304)
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: yes, technical impact: total).
- Record last changed materially (score, affected products, status or references).
References
Advisories
Other references
Our coverage
Recent Missing Critical Step in Authentication vulnerabilities
- 9.1 Critical severity
- 8.1 High severity
- 9.1 Critical severity
- 8.8 High severity
- 7.3 High severity
- 7.3 High severity
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