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CVE Record

CVE-2026-23057: vsock/virtio: Coalesce only linear skb

In the Linux kernel, the following vulnerability has been resolved: vsock/virtio: Coalesce only linear skb vsock/virtio common tries to coalesce buffers in rx queue: if a linear skb (with a spare tail room) is followed by a small skb (length limited by GOOD_COPY_LEN = 128), an attempt is made to join them. Since the introduction of MSG_ZEROCOPY support, assumption that a small skb will always be linear is incorrect. In the zerocopy case, data is lost and the linear skb is appended with uninitialized kernel memory. Of all 3 supported virtio-based transports, only loopback-transport is affected. G2H virtio-transport rx queue operates on explicitly linear skbs; see virtio_vsock_alloc_linear_skb() in virtio_vsock_rx_fill(). H2G vhost-transport may allocate non-linear skbs, but only for sizes that are not considered for coalescence; see PAGE_ALLOC_COSTLY_ORDER in virtio_vsock_alloc_skb(). Ensure only linear skbs are coalesced. Note that skb_tailroom(last_skb) > 0 guarantees last_skb is linear.

UnknownCVSS not scoredNot KEV-listedUpdated
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Glexia's TakeAutomated analysismoderate

Security readout for executives and security teams

Plain-English summary

CVE-2026-23057 is a Linux kernel virtio-vsock bug that can mix uninitialized kernel memory into received data in a specific loopback transport path. This may create information exposure or data integrity risk. Public sources do not provide CVSS, exploitation evidence, or detailed attacker requirements.

Executive priority

Treat as a targeted kernel update item, not an emergency internet-wide issue based on current evidence. Prioritize virtualization platforms and Linux fleets using vsock. Escalate if vendors assign high severity or exploitation evidence appears.

Technical view

The vsock/virtio receive queue coalesces small buffers assuming the following skb is linear. MSG_ZEROCOPY made that assumption unsafe: non-linear skb handling can lose data and append uninitialized kernel memory. The CVE text states only virtio-vsock loopback transport is affected; G2H and H2G paths are excluded by allocation behavior.

Likely exposure

Exposure is most likely on Linux systems using affected kernels with virtio-vsock loopback transport and MSG_ZEROCOPY-relevant traffic. The supplied record lists Linux kernel versions and stable commits, but does not clearly describe distro package status or deployment prevalence.

Exploitation context

CISA KEV is false, and the provided sources do not report active exploitation or a public exploit. Exploitation would require reaching the affected vsock/virtio loopback receive coalescing path; exact privilege and access prerequisites are not stated.

Researcher notes

The record says only loopback-transport is affected and explains why G2H and H2G virtio transports are not. Severity, CVSS, CWE, exploitability, and distro mappings are absent. Version data in the supplied record is limited, so rely on vendor advisories and fixed commits for confirmation.

Mitigation direction

  • Review Linux vendor advisories for CVE-2026-23057 and apply supported kernel updates.
  • Prioritize systems using virtio-vsock loopback transport in virtualization-heavy environments.
  • Confirm installed kernels include one of the referenced stable fixes.
  • If patching is delayed, evaluate reducing exposure to affected vsock loopback use cases.

Validation and detection

  • Inventory Linux kernel versions across hosts and guest environments.
  • Identify systems using virtio-vsock and loopback transport functionality.
  • Check whether the kernel source or package includes the referenced fix commits.
  • Track distribution advisories because package versions may differ from upstream kernel versions.
Prepared
Confidence
medium
Sources
5

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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CVE-2026-23057 mapping review

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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
0ADP providers
4Source 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.

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
LinuxLinux581512a6dc939ef122e49336626ae159f3b8a345, 581512a6dc939ef122e49336626ae159f3b8a345, 581512a6dc939ef122e49336626ae159f3b8a345unaffected
LinuxLinux6.7, 0, 6.12.68, 6.18.8, 6.19affected
Weakness

CWE details

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