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CVE Record

CVE-2025-39718: vsock/virtio: Validate length in packet header before skb_put()

In the Linux kernel, the following vulnerability has been resolved: vsock/virtio: Validate length in packet header before skb_put() When receiving a vsock packet in the guest, only the virtqueue buffer size is validated prior to virtio_vsock_skb_rx_put(). Unfortunately, virtio_vsock_skb_rx_put() uses the length from the packet header as the length argument to skb_put(), potentially resulting in SKB overflow if the host has gone wonky. Validate the length as advertised by the packet header before calling virtio_vsock_skb_rx_put().

UnknownCVSS not scoredNot KEV-listedUpdated
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Glexia's TakeAutomated analysismoderate

Security readout for executives and security teams

Plain-English summary

This is a Linux kernel virtualization bug. A Linux guest receiving virtio-vsock traffic could trust a packet header length before copying data into a socket buffer, creating a possible buffer overflow if the host sends malformed data. The business concern is concentrated in virtualized Linux environments, not ordinary network-facing services.

Executive priority

Treat this as a virtualization hardening update. It is not confirmed as actively exploited, but affected Linux guests using virtio-vsock should be patched through normal emergency or accelerated kernel maintenance, especially where host trust is limited.

Technical view

The vulnerable path is virtio vsock receive handling in the guest. The code validated the virtqueue buffer size but passed the packet header length into skb_put() without first validating that header length, allowing potential SKB overflow. Kernel stable commits add length validation before virtio_vsock_skb_rx_put().

Likely exposure

Exposure is most likely in Linux guests where virtio-vsock is enabled or provided by a virtualization platform. The CVE data lists Linux kernel lines as affected, but distribution and appliance impact depends on vendor packaging and backports.

Exploitation context

The bundle does not show CISA KEV listing, public exploitation, exploit code, or a CVSS score. The described trigger requires a malformed virtio-vsock packet from a faulty or malicious host-side source, so assess host-to-guest trust boundaries carefully.

Researcher notes

Key uncertainty is product-specific reachability. The CVE describes guest receive-side behavior and host-origin malformed packet conditions, but the bundle does not provide crash impact, privilege outcome, CVSS, or exploitability details. Validate against actual kernel config, module usage, and vendor backport status.

Mitigation direction

  • Apply vendor kernel updates that include the referenced stable fixes.
  • Review Debian LTS and Siemens advisories if those environments apply.
  • Check Linux distribution guidance for fixed package versions and backports.
  • Prioritize systems using virtio-vsock in shared or less-trusted virtualization environments.

Validation and detection

  • Inventory Linux guests and record kernel versions.
  • Identify whether virtio-vsock is enabled or required on those guests.
  • Compare kernel packages against distribution advisories and stable fix references.
  • Confirm patched kernels are running after reboot, not only installed.
Prepared
Confidence
medium
Sources
9

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

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Vulnerability profileCVE Program record
Severity
Unknown
CVSS
Not scored
Known Exploited
No
Published
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.

0CVSS vectors
3Timeline events
2ADP providers
8Source links

Vulnerability timeline

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

  1. CVE reservedCVE Program

    The CVE ID was reserved by the assigning CNA.

  2. CVE publishedCVE Program

    The CVE record was published.

  3. CVE updatedCVE Program

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

ADP provider summaries

CVECVE Program Container
siemens-SADPADP container

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
LinuxLinuxbaddcc2c71572968cdaeee1c4ab3dc0ad90fa765, 71dc9ec9ac7d3eee785cdc986c3daeb821381e20, 71dc9ec9ac7d3eee785cdc986c3daeb821381e20, 71dc9ec9ac7d3eee785cdc986c3daeb821381e20, 71dc9ec9ac7d3eee785cdc986c3daeb821381e20, 6.1.63unaffected
LinuxLinux6.3, 0, 6.1.149, 6.6.103, 6.12.44, 6.16.4, 6.17affected
Weakness

CWE details

No CWE listed

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