Kubevirt: virt-handler-rhel9: kubevirt: unbounded virtio-serial readline in virt-handler causes oom denial of service

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Summary

CVECVE-2026-13322
StatePUBLISHED
Assignerredhat
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-06-26 00:16:51 UTC
Updated2026-07-06 17:25:39 UTC
DescriptionA flaw was found in KubeVirt's downward metrics virtio-serial server. The server reads guest requests using textproto.Reader.ReadLine(), which buffers input indefinitely until a newline character is received, with no length limit or read deadline. A user with access to a VM guest that has the downward metrics virtio-serial device configured can write a continuous byte stream to the device, causing unbounded memory allocation in the virt-handler process until it is OOM-killed.

Risk And Classification

Primary CVSS: v3.1 3.8 LOW from [email protected]

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

EPSS: 0.000940000 probability, percentile 0.007510000 (date 2026-07-08)

Problem Types: CWE-770 | CWE-770 Allocation of Resources Without Limits or Throttling

VersionSourceTypeScoreSeverityVector
3.1[email protected]Secondary3.8LOWCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:N/I:N/A:L
3.1CNACVSS3.8LOWCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:N/I:N/A:L

CVSS v3.1 Breakdown

Attack Vector
Local
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Changed
Confidentiality
None
Integrity
None
Availability
Low

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

NVD Known Affected Configurations (CPE 2.3)

TypeVendorProductVersionUpdateEditionLanguage
Application Kubevirt Kubevirt - All All All
Application Redhat Openshift Virtualization All All All All

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Red Hat Red Hat OpenShift Virtualization 4 Not specified Not specified
CNA Red Hat Red Hat OpenShift Virtualization 4 Not specified Not specified

References

ReferenceSourceLinkTags
bugzilla.redhat.com/show_bug.cgi [email protected] bugzilla.redhat.com Issue Tracking, Vendor Advisory
access.redhat.com/security/cve/CVE-2026-13322 [email protected] access.redhat.com Mitigation, Vendor Advisory
CVE Program record CVE.ORG www.cve.org canonical
NVD vulnerability detail NVD nvd.nist.gov canonical, analysis

Vendor Comments And Credit

Discovery Credit

CNA: This issue was discovered by Huzaifa Sidhpurwala (Red Hat). (en)

Additional Advisory Data

SourceTimeEvent
CNA2026-06-25T00:00:00.000ZReported to Red Hat.
CNA2026-06-25T00:00:00.000ZMade public.

Workarounds

CNA: The downward metrics virtio-serial device must be explicitly added to a VM's specification to be present. Clusters that do not use this feature are not exposed. To reduce exposure, administrators can restrict the ability to configure downward metrics devices on tenant VMs by using an admission webhook or policy controller such as Gatekeeper/OPA.

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