CVE-2026-51082
Received Received - Intake

Race Condition in Proxmox Virtual Environment VNC Session Hijacking

Publication date: 2026-07-17

Last updated on: 2026-07-17

Assigner: MITRE

Description
A race condition between the vncproxy and vncwebsocket API calls in Proxmox Virtual Environment (PVE) 9.x pve-manager before 9.1.9 and 8.x before 8.4.19; qemu-server 9.x before 9.1.7 and 8.x before 8.4.7; and pve-container before 6.1.3 (PVE 9.x) and before 5.3.4 (PVE 8.x) 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.

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Meta Information

Published
2026-07-17
Last Modified
2026-07-17
Generated
2026-07-17
AI Q&A
2026-07-17
EPSS Evaluated
N/A
NVD
CVE-2026-51082
EUVD
EUVD-2026-45182

Affected Vendors & Products

Showing 6 associated CPEs
Vendor Product Version / Range
proxmox pve_manager to 9.1.9 (exc)
proxmox qemu_server to 9.1.7 (exc)
proxmox pve_container to 6.1.3 (exc)
proxmox pve_container to 5.3.4 (exc)
proxmox pve_manager to 8.4.19 (exc)
proxmox qemu_server to 8.4.7 (exc)

Helpful Resources

Exploitability

CWE
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KEV
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CWE ID Description
CWE-362 The product contains a concurrent code sequence that requires temporary, exclusive access to a shared resource, but a timing window exists in which the shared resource can be modified by another code sequence operating concurrently.

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Executive Summary

This vulnerability is a race condition in Proxmox Virtual Environment (PVE) 9.x and 8.4.x versions. It occurs between the vncproxy and vncwebsocket API calls, allowing an attacker with privileges to hijack a VNC session established by another user for a different VM.

Detection Guidance

This vulnerability involves a race condition in Proxmox VE components. Detection requires checking installed versions of pve-manager, qemu-server, and pve-container against the patched versions (9.1.9/8.4.19 for pve-manager, 9.1.7/8.4.7 for qemu-server, and 6.1.3/5.3.4 for pve-container). No specific commands are provided in the context to detect active exploitation.

Impact Analysis

An attacker could gain unauthorized access to a victim's VM session, potentially viewing or manipulating sensitive data, executing commands, or taking control of the virtual machine.

Compliance Impact

This vulnerability could lead to unauthorized access to personal or health data, violating GDPR or HIPAA compliance. It may result in data breaches, unauthorized disclosures, and failure to meet regulatory requirements for data protection and access controls.

Mitigation Strategies

Update Proxmox VE components to patched versions: pve-manager 9.1.9 or 8.4.19, qemu-server 9.1.7 or 8.4.7, and pve-container 6.1.3 or 5.3.4. Restrict user privileges to prevent unauthorized VNC session hijacking attempts.

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