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CVE Record

CVE-2026-23069: vsock/virtio: fix potential underflow in virtio_transport_get_credit()

In the Linux kernel, the following vulnerability has been resolved: vsock/virtio: fix potential underflow in virtio_transport_get_credit() The credit calculation in virtio_transport_get_credit() uses unsigned arithmetic: ret = vvs->peer_buf_alloc - (vvs->tx_cnt - vvs->peer_fwd_cnt); If the peer shrinks its advertised buffer (peer_buf_alloc) while bytes are in flight, the subtraction can underflow and produce a large positive value, potentially allowing more data to be queued than the peer can handle. Reuse virtio_transport_has_space() which already handles this case and add a comment to make it clear why we are doing that. [Stefano: use virtio_transport_has_space() instead of duplicating the code] [Stefano: tweak the commit message]

UnknownCVSS not scoredNot KEV-listedUpdated
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Glexia's TakeAutomated analysisunknown

Security readout for executives and security teams

Plain-English summary

CVE-2026-23069 is a Linux kernel virtio-vsock bug in virtual socket flow control. A buffer-credit calculation can wrap around when a peer reduces its advertised buffer while data is in flight, making the sender believe more space exists than actually does.

Executive priority

Treat as a kernel maintenance priority with higher attention for virtualization-heavy environments. Business urgency is uncertain because no CVSS, KEV listing, exploitation evidence, or concrete impact rating is provided in the source bundle.

Technical view

The issue is in virtio_transport_get_credit(). Unsigned subtraction between peer_buf_alloc, tx_cnt, and peer_fwd_cnt can underflow and return an excessively large credit value. The resolved fix reuses virtio_transport_has_space(), which already handles the buffer-shrink case safely.

Likely exposure

Exposure is most relevant to Linux systems using virtio-vsock in virtualized environments. The CVE data identifies Linux kernel versions and stable commit fixes, but does not provide distribution-specific package names or enabled-by-default deployment conditions.

Exploitation context

The provided sources do not show active exploitation, and KEV is false. The stated risk is potential over-queuing beyond what the peer can handle; the public bundle does not classify final impact such as denial of service, privilege escalation, or data exposure.

Researcher notes

The core condition is an unsigned arithmetic underflow in virtio vsock credit accounting during peer buffer shrinkage. The fix delegates space calculation to virtio_transport_has_space(). The bundle lacks reproducer details, exploitability analysis, and distro mapping.

Mitigation direction

  • Check Linux vendor advisories for patched kernel packages containing the referenced stable fixes.
  • Prioritize kernel updates on virtualized systems that use virtio-vsock.
  • If immediate patching is not possible, review whether virtio-vsock is required in exposed workloads.
  • Track distribution backports rather than relying only on upstream version numbers.

Validation and detection

  • Inventory Linux kernel versions across virtualized hosts and guests.
  • Confirm whether running kernels include one of the referenced stable fix commits.
  • Identify workloads using virtio-vsock or AF_VSOCK functionality.
  • Review vendor advisories for distribution-specific affected and fixed package versions.
Prepared
Confidence
medium
Sources
7

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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ATT&CK lookup starting points

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CVE-2026-23069 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
1ADP providers
6Source links

SSVC decision data

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

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

CISA-ADPCISA ADP Vulnrichment
other:ssvc

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
LinuxLinux06a8fc78367d070720af960dcecec917d3ae5f3b, 06a8fc78367d070720af960dcecec917d3ae5f3b, 06a8fc78367d070720af960dcecec917d3ae5f3b, 06a8fc78367d070720af960dcecec917d3ae5f3b, 06a8fc78367d070720af960dcecec917d3ae5f3bunaffected
LinuxLinux4.8, 0, 6.1.162, 6.6.122, 6.12.68, 6.18.8, 6.19affected
Weakness

CWE details

No CWE listed

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