Skip to main content

Xen Hypervisor CVE-2026-42489

| EUVDEUVD-2026-37889 MEDIUM
Improper Locking (CWE-667)
2026-06-09 GHSA-vw8q-74w5-57vq
Python Information Disclosure
5.3
CVSS 3.1 · Vendor
Share

Severity by source

Vendor (CNA) PRIMARY
5.3 MEDIUM
AV:L/AC:H/PR:H/UI:N/S:C/C:N/I:N/A:H
SUSE
MEDIUM
qualitative

Primary rating from Vendor (CNA).

CVSS VectorVendor

CVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:C/C:N/I:N/A:H
Attack Vector
Local
Attack Complexity
High
Privileges Required
High
User Interaction
None
Scope
Changed
Confidentiality
None
Integrity
None
Availability
High

Lifecycle Timeline

3
Severity Changed
Jun 18, 2026 - 19:38 NVD
CRITICAL MEDIUM
CVSS changed
Jun 18, 2026 - 19:38 NVD
5.3 (CRITICAL) 5.3 (MEDIUM)
Analysis Generated
Jun 09, 2026 - 14:17 vuln.today

Description PRE-NVD

Disclosed via oss-security. NVD scoring and full description are pending.

Articles & Coverage 1

News Critical Denial of Service in Python via Xen domctl Lock Abuse - CVE-2026-42489 Jun 09, 2026

AnalysisAI

Denial of service against Xen host management is possible through deliberate abuse of the unfair domctl system-wide lock, affecting all Xen versions from 3.3 onwards. A less-privileged domain can monopolize the lock used to serialize guest creation and management operations, starving the control domain or equally/more-privileged entities of lock access and potentially rendering the entire host unmanageable. No public exploit identified at time of analysis, and no CVSS score was published with XSA-492.

Technical ContextAI

Xen's domctl interface is the primary mechanism through which the control domain, a possible Xenstore domain, or a domain managing a specific guest creates and administers guest VMs. Because certain domctl operations cannot safely execute concurrently, a system-wide lock serializes them. CVE-2026-42489 is specifically the lock fairness deficiency: the acquisition path does not implement any fairness or priority ordering, meaning a lower-privileged domain that aggressively contends for the lock can cause indefinite starvation of higher-priority requestors. This maps to CWE-667 (Improper Locking) / CWE-362 (Concurrent Execution Using Shared Resource with Improper Synchronization). The companion issue CVE-2026-42490 (same XSA-492 advisory) is distinct: when XSM/Flask mandatory access control is in use, lock acquisition occurs before permission checks for some operations, allowing the lock to be held before authorization is verified. No CWE identifier was formally assigned in the advisory data.

Affected ProductsAI

All Xen Hypervisor releases from version 3.3 onwards are confirmed vulnerable per the XSA-492 advisory. Versions prior to 3.3 use a different locking implementation but may also be vulnerable. Patch sets have been released for Xen 4.17.x (18 patches), 4.18.x (19 patches), 4.19.x, 4.20.x, 4.21.x, and xen-unstable. No CPE strings were included in the source data. The Xen Project security policy page is at http://www.xenproject.org/security-policy.html and the full advisory is at https://seclists.org/oss-sec/2026/q2/858.

RemediationAI

Apply the XSA-492 patch set appropriate for the installed Xen branch, available for Xen 4.17.x through 4.21.x and xen-unstable via the Xen Security Advisory at https://seclists.org/oss-sec/2026/q2/858. Downstreams should update to the tip of the relevant stable branch before applying, as patches are prepared against stable branches and may not cleanly apply to release tarballs. Critically, for Xen 4.21 and staging (xen-unstable), the patches include an adjustment to the default XSM/Flask policy; environments running custom Flask policies must manually apply a corresponding policy change or the XSM/Flask permission check bypass (CVE-2026-42490) will remain. No known mitigation exists - the advisory explicitly states 'There is no known mitigation,' so compensating controls such as restricting domctl access via XSM/Flask policies may reduce exposure to CVE-2026-42490 but do not address the CVE-2026-42489 lock fairness flaw itself.

More in Python

View all
CVE-2025-24016 CRITICAL POC
9.9 Feb 10

Wazuh SIEM platform versions 4.4.0 through 4.9.0 contain an unsafe deserialization vulnerability in the DistributedAPI t
CVE-2025-27520 CRITICAL POC
9.8 Apr 04

BentoML version 1.4.2 and earlier contains an unauthenticated remote code execution vulnerability through insecure deser
CVE-2025-2945 CRITICAL POC
9.9 Apr 03

pgAdmin 4 contains critical remote code execution vulnerabilities in the Query Tool download and Cloud Deployment endpoi
CVE-2013-5093 MEDIUM POC
6.8 Sep 27

The renderLocalView function in render/views.py in graphite-web in Graphite 0.9.5 through 0.9.10 uses the pickle Python

CVE-2025-32375 CRITICAL POC
9.8 Apr 09

BentoML is a Python library for building online serving systems optimized for AI apps and model inference. Rated critica
CVE-2014-0224 HIGH POC
7.4 Jun 05

OpenSSL before 0.9.8za, 1.0.0 before 1.0.0m, and 1.0.1 before 1.0.1h does not properly restrict processing of ChangeCiph
CVE-2024-21644 HIGH POC
7.5 Jan 08

pyLoad download manager version prior to 0.5.0b3.dev77 exposes the Flask SECRET_KEY through an unauthenticated endpoint.
CVE-2017-9462 HIGH POC
8.8 Jun 06

In Mercurial before 4.1.3, "hg serve --stdio" allows remote authenticated users to launch the Python debugger, and conse
CVE-2026-39987 CRITICAL POC
9.3 Apr 08

Unauthenticated remote code execution in Marimo ≤0.20.4 allows attackers to execute arbitrary system commands via the `/
CVE-2024-21645 MEDIUM POC
5.3 Jan 08

pyLoad is the free and open-source Download Manager written in pure Python. Rated medium severity (CVSS 5.3), this vulne
CVE-2026-33017 CRITICAL POC
9.3 Mar 17

Langflow (a visual LLM pipeline builder) contains a critical unauthenticated code execution vulnerability (CVE-2026-3301
CVE-2026-55255 HIGH POC
8.4 Jun 19

Cross-user flow execution in Langflow (< 1.9.1) lets any authenticated API-key holder run another user's flow by passing

Same weakness CWE-667 – Improper Locking

View all
CVE-2025-43510 HIGH POC
7.8
CVE-2019-5886 CRITICAL POC
9.8
CVE-2020-13246 HIGH POC
7.5
CVE-2019-15513 HIGH POC
7.5
CVE-2019-11599 HIGH POC
7.0
CVE-2023-21400 MEDIUM POC
6.7
CVE-2021-20291 MEDIUM POC
6.5
CVE-2026-53049 CRITICAL
9.8

Same technique Information Disclosure

View all
CVE-2013-2251 CRITICAL POC
9.8
CVE-2017-5638 CRITICAL POC
9.8
CVE-2025-24813 CRITICAL POC
9.8
CVE-2015-1701 HIGH POC
7.8
CVE-2017-0147 HIGH POC
7.5
CVE-2014-6324 HIGH POC
8.8
CVE-2023-7028 CRITICAL POC
10.0
CVE-2024-24919 HIGH POC
8.6

Vendor StatusVendor

SUSE

Severity: Medium
Product Status
SUSE Linux Enterprise High Performance Computing 15 SP5-ESPOS Affected
SUSE Linux Enterprise High Performance Computing 15 SP5-LTSS Affected
SUSE Linux Enterprise Micro 5.5 Affected
SUSE Linux Enterprise Module for Basesystem 15 SP7 Affected
SUSE Linux Enterprise Server 15 SP7 Affected

Share

CVE-2026-42489 vulnerability details – vuln.today
Back

This site uses cookies essential for authentication and security. No tracking or analytics cookies are used. Privacy Policy