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CVE-2026-13218 Red Hat CVE debrief

A flaw was found in KubeVirt's virt-handler network cache handling. The WriteToCachedFile function writes data to a launcher-rooted path using os.WriteFile and os.Chown without symlink protection. A user with access to the virt-launcher container can plant a symlink at the cache file path, causing virt-handler to follow it and overwrite an arbitrary host file with JSON content and change its ownership. This medium-severity vulnerability requires access to the virt-launcher container and has a CVSS score of 4.2. Users of KubeVirt, particularly those with access to the virt-launcher container, should be aware of this flaw and take steps to mitigate it.

Vendor
Red Hat
Product
Red Hat OpenShift Virtualization 4
CVSS
MEDIUM 4.2
CISA KEV
Not listed in stored evidence
Original CVE published
2026-06-26
Original CVE updated
2026-07-06
Advisory published
2026-06-26
Advisory updated
2026-07-06

Who should care

Users of KubeVirt, particularly those with access to the virt-launcher container, should be aware of this medium-severity flaw and take steps to mitigate it. Affected operator, platform, vulnerability-management, and security teams should prioritize patching or mitigation efforts.

Technical summary

The WriteToCachedFile function in KubeVirt's virt-handler writes data to a launcher-rooted path using os.WriteFile and os.Chown without symlink protection. This allows a user with access to the virt-launcher container to plant a symlink at the cache file path, causing virt-handler to follow it and overwrite an arbitrary host file with JSON content and change its ownership. The flaw requires access to the virt-launcher container and has a CVSS score of 4.2, indicating a medium-severity vulnerability.

Defensive priority

Medium priority, as the flaw requires access to the virt-launcher container and has a CVSS score of 4.2. Recommended actions include applying vendor patches, restricting access to the virt-launcher container, and monitoring for suspicious activity.

Recommended defensive actions

  • Apply the vendor patch or update to a fixed version of KubeVirt
  • Restrict access to the virt-launcher container
  • Monitor for suspicious activity related to virt-handler and cache files
  • Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up.
  • Review the supplied official advisory or CVE record to validate affected scope, severity, and vendor guidance.

Evidence notes

The CVE record was published on 2026-06-26T00:16:51.147Z and last modified on 2026-07-06T17:46:14.380Z. The NVD entry is currently Analyzed. Evidence is limited to CVE and NVD information; further verification is recommended. Defensive verification tasks include reviewing vendor advisories and tracking affected systems.

Sources and references

Verified primary and authoritative sources

  • CVE-2026-13218 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2026-13218

    CVE Program - Official CVE Program record with source-provided CVE metadata.

  • CVE-2026-13218 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2026-13218

    NIST National Vulnerability Database - Official NIST NVD detail page and source-specific vulnerability assessment.

Supplemental references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.