dbcve.org
Linux KernelOperating system · Linux

CVE-2026-52994

MEDIUM · 5.5 CVSS v3.1 Published 2026-06-24
Fix available
A fix is available. Upgrade to 6.18.33 / 7.0.10 or later.
See remediation →
57/100
Remediation priority · Elevated
Zero-click Patch available 8 weeks old

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
In the Linux kernel, the following vulnerability has been resolved: vsock/virtio: fix MSG_ZEROCOPY pinned-pages accounting virtio_transport_init_zcopy_skb() uses iter->count as the size argument for msg_zerocopy_realloc(), which in turn passes it to mm_account_pinned_pages() for RLIMIT_MEMLOCK accounting. However, this function is called after virtio_transport_fill_skb() has already consumed the iterator via __zerocopy_sg_from_iter(), so on the last skb, iter->count will be 0, skipping the RLIMIT_MEMLOCK enforcement. Pass pkt_len (the total bytes being sent) as an explicit parameter to virtio_transport_init_zcopy_skb() instead of reading the already-consumed iter->count. This matches TCP and UDP, which both call msg_zerocopy_realloc() with the original message size.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

The vsock/virtio transport in the Linux kernel fails to properly enforce RLIMIT_MEMLOCK during MSG_ZEROCOPY operations. After virtio_transport_fill_skb() consumes the iterator via __zerocopy_sg_from_iter(), subsequent calls to virtio_transport_init_zcopy_skb() read iter->count which becomes 0 on the last skb, causing memory pinning accounting to be skipped entirely. This allows local users to bypass memory locking limits.

MitigationApply the upstream kernel patch to pass pkt_len (total bytes being sent) as an explicit parameter to virtio_transport_init_zcopy_skb() instead of relying on the consumed iter->count, matching TCP/UDP behavior.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
Linux KernelOperating system
Affected:>= 6.7, < 6.18.33>= 6.19, < 7.0.10

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Local
Complexity
Low
Privileges
Low
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

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

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Check the running kernel version
    Run 'uname -r' or 'cat /proc/version' to get the kernel version
    Affected if The version is >= 6.7 and < 6.18.33, or >= 6.19 and < 7.0.10
  2. Verify vsock/virtio transport is in use
    Check for loaded vsock modules with 'lsmod | grep vsock' or check for vsock device nodes in /dev or /sys/class/vsock
    Affected if vsock modules are loaded or vsock devices exist in the environment
  3. Confirm MSG_ZEROCOPY capability is active
    Check if the kernel supports zerocopy by looking for CONFIG_ZEROCOPY in /boot/config-$(uname -r) or check socket options with 'ss -zerocopy'
    Affected if Zerocopy support is compiled in and available for vsock sockets
  4. Inspect current RLIMIT_MEMLOCK settings
    Run 'ulimit -l' or 'cat /proc/self/limits' to see the current memory lock limits
    Affected if RLIMIT_MEMLOCK is set to a finite value (not unlimited) - this indicates the bypass could allow exceeding this limit

A system is affected if it runs a vulnerable kernel version (6.7 to 6.18.32, 6.19 to 7.0.9) with vsock/virtio transport and zerocopy support enabled, allowing local users to exceed their RLIMIT_MEMLOCK when using MSG_ZEROCOPY with vsock.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to 6.18.33 / 7.0.10 or later
Fixed in 6.18.337.0.10
Vendor patch git.kernel.org →
Interim mitigation

Apply the upstream kernel patch to pass pkt_len (total bytes being sent) as an explicit parameter to virtio_transport_init_zcopy_skb() instead of relying on the consumed iter->count, matching TCP/UDP behavior.

Recommended fix High confidence

Linux Kernel 6.18.33 or later, or 7.0.10 or later

  1. Identify the current running Linux kernel version using 'uname -r'
  2. Upgrade the Linux kernel to version 6.18.33 or later for the 6.x branch, or version 7.0.10 or later for the 7.x branch
  3. Reboot the system to load the fixed kernel
  4. Verify the fix is applied by checking the kernel version and reviewing the git commit for virtio_transport_init_zcopy_skb changes
Caveat Kernel upgrades may require rebuilding out-of-tree kernel modules; ensure compatibility with existing system configurations

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Linux Kernel Scoped from the published advisory
  • Consultation1.0 h
  • Implementation2.0 h
  • Testing2.0 h
  • Review / QA2.0 h
7.0 hours of engineering $1,220
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $1,952.

Scan for this in your stack

Free · runs locally
dbcve dependency scanner

Check whether your project pulls in CVE-2026-52994 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.

Get it on GitHub Scan in the browser

References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-52994 in production — separate from our analysis above.

No notes yet

Be the first to add a field note for this CVE — a mitigation you’ve verified, a version caveat, or a link to a working fix. Sign in above to contribute.

What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data