What is the CVSS score of CVE-2026-51082?

CVE-2026-51082 has a CVSS 3.1 base score of 7.2 (High). CVSS vector: CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H. EPSS exploitation probability: 0.2%.

Which versions of Proxmox VE are affected by CVE-2026-51082?

Proxmox Virtual Environment (PVE) 9.x and 8.4.x contain a session hijacking vulnerability that allows authenticated users with vncproxy API rights to seize VNC console sessions opened by other users,…

How to fix or mitigate CVE-2026-51082?

Within 24 hours: Inventory all PVE 9.x and 8.4.x instances and document which users hold vncproxy API permissions; review access logs for vncproxy and vncwebsocket calls to identify any anomalous session takeovers. Within 7 days: Implement role-based access controls to restrict vncproxy permissions to only essential administrators; disable VNC console access entirely if operationally unnecessary; configure alerting for concurrent vncproxy API calls from multiple users targeting the same virtual machine. Within 30 days: Monitor Proxmox security advisories for a vendor-released patch addressing CWE-362 in PVE 9.x and 8.4.x, and schedule immediate deployment upon availability.

Proxmox VE CVE-2026-51082

EUVD-2026-45182 HIGH

Race Condition (CWE-362)

2026-07-17 mitre

GHSA-vjf4-fxgw-f2mh

Information Disclosure Race Condition N A

7.2

CVSS 3.1 · Vendor: mitre

Severity by source

Vendor (mitre) PRIMARY

7.2 HIGH

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

vuln.today AI

7.5 HIGH

Race condition dependent on a parallel victim session raises AC to H; needs an authenticated user with VM.Console (PR:L), and a hijacked console yields full C/I/A over the target VM.

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

4.0 AV:N/AC:H/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N

Primary rating from Vendor (mitre).

CVSS VectorVendor: mitre

Attack Vector

Network

Attack Complexity

Low

Privileges Required

High

User Interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

High

Availability

High

Lifecycle Timeline

Analysis Generated

Jul 17, 2026 - 17:23 vuln.today

CVSS changed

Jul 17, 2026 - 17:22 NVD

7.2 (HIGH)

CVE Published

Jul 17, 2026 - 00:00 cve.org

UNKNOWN (no severity yet)

CVE Published

Jul 17, 2026 - 00:00 cve.org

HIGH 7.2

DescriptionCVE.org

A race condition between the vncproxy and vncwebsocket API calls in Proxmox Virtual Environment (PVE) 9.x pve-manager 9.1.x before 9.1.9 and 8.4.x before 8.4.19; qemu-server 9.1.x before 9.1.7 and 8.4.x before 8.4.7; and pve-container 6.1.x before 6.1.3 and 5.3.x before 5.3.4 allows an attacker with privileges to call "vncproxy" to hijack a VNC session that is established in parallel by a different user for a different VM.

AnalysisAI

Session hijacking in Proxmox Virtual Environment (PVE 9.x/8.4.x) lets an authenticated user with rights to call the "vncproxy" API race the parallel "vncwebsocket" call and seize a VNC console session that a different user legitimately opened for a different VM. The flaw (CWE-362, CVSS 7.2) grants full interactive console access to another tenant's virtual machine, breaking isolation between users. There is no public exploit identified at time of analysis and it is not listed in CISA KEV.

Technical ContextAI

Proxmox VE exposes VM/CT console access through a two-step API flow: a client first calls vncproxy to spin up a proxied VNC server for a specific VM and obtain a one-time ticket/port, then completes the connection via the vncwebsocket endpoint that upgrades to the actual VNC stream. CWE-362 (Race Condition) here is a time-of-check/time-of-use style flaw: because the pairing between the vncproxy allocation and the vncwebsocket consumer is not atomically bound to the requesting user and target VM, two console requests happening in parallel can be crossed, so one user's websocket attaches to another user's freshly-allocated VNC session. The fix spans three affected components - pve-manager (the web UI/API daemon that brokers the calls), qemu-server (VM/QEMU console handling), and pve-container (LXC console handling) - indicating the defective handshake logic is shared across both VM and container console paths. The CPE data is uninformative (a placeholder 'n/a' string), so exact affected product identification comes from the version ranges in the description, not from structured CPE.

RemediationAI

Vendor-released patch: upgrade pve-manager to 9.1.9 (8.x line: 8.4.19), qemu-server to 9.1.7 (8.x line: 8.4.7), and pve-container to 6.1.3 (5.x line: 5.3.4); apply all three together via the standard Proxmox repositories (apt update && apt full-upgrade) since the fix is split across the console-handling packages, then restart the pveproxy/pvedaemon services as directed. Until patched, reduce exposure by tightening console permissions: revoke VM.Console from users who do not strictly need interactive console access so fewer accounts can call vncproxy, and restrict access to the API/web UI (TCP 8006) to trusted management networks or a VPN to shrink the pool of accounts that could race a session - the trade-off is that legitimate delegated console users lose noVNC/console access until re-granted. Avoid encouraging many users to open consoles simultaneously on shared clusters while unpatched. Track the official advisory at https://forum.proxmox.com/threads/proxmox-virtual-environment-security-advisories.149331/post-849971.