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CVE Record

CVE-2025-11234: Qemu-kvm: vnc websocket handshake use-after-free

A flaw was found in QEMU. If the QIOChannelWebsock object is freed while it is waiting to complete a handshake, a GSource is leaked. This can lead to the callback firing later on and triggering a use-after-free in the use of the channel. This can be abused by a malicious client with network access to the VNC WebSocket port to cause a denial of service during the WebSocket handshake prior to the VNC client authentication.

HighCVSS 7.5Not KEV-listedUpdated
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Glexia's TakeAutomated analysishigh

Security readout for executives and security teams

Plain-English summary

This flaw can let an unauthenticated client crash or disrupt QEMU VNC WebSocket service during the initial handshake. The main business risk is loss of availability for virtualization hosts or platforms exposing that interface, not data theft or tampering based on the supplied evidence.

Executive priority

Treat this as a high-priority availability risk for virtualization infrastructure, especially if VNC WebSocket access crosses trust boundaries. It is not currently evidenced as exploited in the supplied sources, but unauthenticated pre-auth network DoS raises operational urgency.

Technical view

CVE-2025-11234 is a QEMU use-after-free in QIOChannelWebsock when a WebSocket handshake is interrupted. A leaked GSource callback can later use a freed channel. The CVSS 3.1 score is 7.5, network exploitable, low complexity, no privileges, no user interaction, availability impact only.

Likely exposure

Exposure is most likely where Red Hat qemu-kvm, virt:rhel, or OpenShift RHCOS builds listed as affected are installed and VNC over WebSocket is reachable by untrusted networks or tenants.

Exploitation context

The bundle does not show CISA KEV listing or active exploitation. The described abuse requires network access to the VNC WebSocket port and occurs before VNC client authentication, making exposed management or virtualization interfaces the concern.

Researcher notes

The affected surface is the WebSocket handshake path before VNC authentication. The supplied data supports denial of service via use-after-free, but does not support claims of code execution, data compromise, or active exploitation.

Mitigation direction

  • Apply the applicable Red Hat errata for the affected RHEL or OpenShift stream.
  • Check Red Hat CVE guidance before assuming a fixed version for your platform.
  • Restrict untrusted network access to VNC WebSocket interfaces where operationally feasible.
  • Prioritize externally reachable or tenant-accessible virtualization management networks first.
  • Monitor virtualization hosts for unexplained QEMU process crashes or availability loss.

Validation and detection

  • Inventory qemu, qemu-kvm, virt:rhel, and RHCOS versions against the affected list.
  • Identify systems where VNC WebSocket service is enabled or reachable over the network.
  • Map each affected product stream to the relevant Red Hat advisory.
  • Confirm patched systems no longer report affected package versions.
  • Review access controls around virtualization management networks and exposed VNC WebSocket ports.
Prepared
Confidence
medium
Sources
10

Public sources used

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

Conservative CVE-to-ATT&CK context

These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.

ATT&CK lookup starting points

Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.

cwe · low confidence lookup

CWE-416: Exact CWE lookup

Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.

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description · low confidence lookup

Container behavior lookup

The affected technology mentions containers, so container-specific ATT&CK technique review may help. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.

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cve · low confidence lookup

CVE-2025-11234 mapping review

Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.

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Vulnerability profileCVE Program record
Severity
High
CVSS
7.5 (3.1)
Known Exploited
No
Published

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

Official CVE source material

CNA and ADP enrichment extracted from CVE v5

These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.

1CVSS vectors
5Timeline events
1ADP providers
13Source links

SSVC decision data

CISA-ADPCISA Coordinator
Timestamp
Version
2.0.3
Exploitation: noneAutomatable: noTechnical Impact: partial

CVSS vector scores

1 official score

We collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.

ScoreVersionSeverityVectorExploitImpactSource
7.5CVSS 3.1HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H3.93.6redhat

Vulnerability scoring details

Base CVSS 3.1 score

7.5High
CVSS 3.1 vector shape for CVE-2025-11234Attack VectorAttack ComplexityPrivileges RequiredUser InteractionScopeConfidentiality ImpactIntegrity ImpactAvailability Impact

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

Attack Vector
NetworkAdjacentLocalPhysical
Attack Complexity
LowHigh
Privileges Required
NoneLowHigh
User Interaction
NoneRequired
Scope
ChangedUnchanged
Confidentiality Impact
HighLowNone
Integrity Impact
HighLowNone
Availability Impact
HighLowNone

Vulnerability timeline

Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.

  1. Source timelineredhat

    Reported to Red Hat.

  2. Source timelineredhat

    Made public.

  3. CVE reservedCVE Program

    The CVE ID was reserved by the assigning CNA.

  4. CVE publishedCVE Program

    The CVE record was published.

  5. CVE updatedCVE Program

    The CVE record metadata indicates this as the latest update time.

ADP provider summaries

CISA-ADPCISA ADP Vulnrichment
other:ssvc

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
Unknown vendorqemuqemu, 2.6.0unaffected
Red HatRed Hat Enterprise Linux 10qemu-kvm, 18:10.0.0-14.el10_1.5affected
Red HatRed Hat Enterprise Linux 8virt-devel:rhel, 8100020251120003312.489197e6affected
Red HatRed Hat Enterprise Linux 8virt:rhel, 8100020251202222937.489197e6affected
Red HatRed Hat Enterprise Linux 9qemu-kvm, 17:10.1.0-17.el9_8affected
Red HatRed Hat Enterprise Linux 9.0 Update Services for SAP Solutionsqemu-kvm, 17:6.2.0-11.el9_0.10affected
Red HatRed Hat Enterprise Linux 9.2 Update Services for SAP Solutionsqemu-kvm, 17:7.2.0-14.el9_2.24affected
Red HatRed Hat Enterprise Linux 9.4 Extended Update Supportqemu-kvm, 17:8.2.0-11.el9_4.18affected
Red HatRed Hat Enterprise Linux 9.4 Extended Update Supportqemu-kvm, 17:8.2.0-11.el9_4.19affected
Red HatRed Hat OpenShift Container Platform 4.16rhcos, 416.94.202601071926-0affected
Red HatRed Hat OpenShift Container Platform 4.17rhcos, 417.94.202601120213-0affected
Red HatRed Hat OpenShift Container Platform 4.18rhcos, 418.94.202601071817-0affected
Red HatRed Hat Enterprise Linux 6qemu-kvmunaffected
Red HatRed Hat Enterprise Linux 7qemu-kvmunaffected
Red HatRed Hat Enterprise Linux 7qemu-kvm-maaffected
Weakness

CWE details

CWE-416

CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.

CWE-416 · source CWE mapping

Use After Free

Use After Free represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.

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