CVE-2023-54391CWE-304

CVE-2023-54391

Critical · published September 2, 2026

CVSS v3.1
9.8
EPSS
0%
Percentile
39.3
In the wild
Unconfirmed
What it is

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.

The record
Technical detail
CVSS v3.1
9.8 · CRITICAL
Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
CVSS v4.0
9.3 · 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
0.00475 · 39.3th percentile
Weakness
CWE-304 · Missing Critical Step in Authentication
Published
2026-09-02T02:17Z
References (7)
https://forum.proxmox.com/threads/proxmox-virtual-environment-security-advisories.149331/page-4#post-867929 · [email protected]https://git.proxmox.com/?p=pve-access-control.git;a=commit;h=032e7d6d441f89a48cadfd7f47e957c8a561c022 · [email protected]https://git.proxmox.com/?p=pve-access-control.git;a=commit;h=032e7d6d441f89a48cadfd7f47e957c8a561c022 · [email protected]https://git.proxmox.com/?p=pve-access-control.git;a=commit;h=032e7d6d441f89a48cadfd7f47e957c8a561c022 · [email protected]https://git.proxmox.com/?p=pve-access-control.git;a=commit;h=032e7d6d441f89a48cadfd7f47e957c8a561c022 · [email protected]https://git.proxmox.com/?p=pve-access-control.git;a=commit;h=0f3d14d6be4d9f23e511701696a529ef3b7ffd61 · [email protected]https://www.vulncheck.com/advisories/proxmox-ve-authentication-bypass-via-tfa-challenge-parameter · [email protected]
EPSS history
Timeline
  • 03 SEP 03:20Z
    EPSS moved — → 0%
    epss
  • 01 SEP 21:59Z
    Proxmox VE 7.0-8.0 Authentication Bypass via tfa-challenge Parameter
    cvelistv5