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Debian LinuxOperating system · Debian

CVE-2022-23042

HIGH · 7.0 CVSS v3.1 Published 2022-03-10
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
72/100
Remediation priority · Elevated
Zero-click

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
Linux PV device frontends vulnerable to attacks by backends T[his CNA information record relates to multiple CVEs; the text explains which aspects/vulnerabilities correspond to which CVE.] Several Linux PV device frontends are using the grant table interfaces for removing access rights of the backends in ways being subject to race conditions, resulting in potential data leaks, data corruption by malicious backends, and denial of service triggered by malicious backends: blkfront, netfront, scsifront and the gntalloc driver are testing whether a grant reference is still in use. If this is not the case, they assume that a following removal of the granted access will always succeed, which is not true in case the backend has mapped the granted page between those two operations. As a result the backend can keep access to the memory page of the guest no matter how the page will be used after the frontend I/O has finished. The xenbus driver has a similar problem, as it doesn't check the success of removing the granted access of a shared ring buffer. blkfront: CVE-2022-23036 netfront: CVE-2022-23037 scsifront: CVE-2022-23038 gntalloc: CVE-2022-23039 xenbus: CVE-2022-23040 blkfront, netfront, scsifront, usbfront, dmabuf, xenbus, 9p, kbdfront, and pvcalls are using a functionality to delay freeing a grant reference until it is no longer in use, but the freeing of the related data page is not synchronized with dropping the granted access. As a result the backend can keep access to the memory page even after it has been freed and then re-used for a different purpose. CVE-2022-23041 netfront will fail a BUG_ON() assertion if it fails to revoke access in the rx path. This will result in a Denial of Service (DoS) situation of the guest which can be triggered by the backend. CVE-2022-23042

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

CVE-2022-23042 is a vulnerability in Linux paravirtualized device frontends (blkfront, netfront, scsifront, usbfront, dmabuf, xenbus, 9p, kbdfront, pvcalls) where freeing of grant references is not synchronized with dropping granted access. This allows malicious backends to retain access to memory pages after they have been freed and reallocated for other purposes, leading to potential data leaks, data corruption, and denial of service.

MitigationApply kernel patches that properly synchronize grant reference freeing with access revocation; ensure Xen hypervisor and toolstack are also updated to compatible versions to prevent backend exploitation.

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
Debian LinuxOperating system
Affected:= 9.0
XenOperating system
Affected:all versions

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
High
Privileges
Low
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/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 if running as a Xen virtual machine
    Examine /proc/xen or run 'xl list' or check for xenfs mount: 'mount | grep xen'
    Affected if The system is a Xen paravirtualized guest or host using Xen virtualization
  2. Verify Xen frontend drivers are loaded
    Run 'lsmod | grep -E "(blkfront|netfront|scsifront|usbfront|dmabuf|xenbus|9p|kbdfront|pvcalls)"' to list loaded frontend drivers
    Affected if One or more of the listed frontend drivers are loaded
  3. Check kernel version
    Run 'uname -r' to get the running kernel version
    Affected if The kernel version is from an unpatched Debian 9.0 or older Xen-compatible kernel (compare against vendor security advisories)
  4. Verify grant table usage is active
    Check /proc/xen/balloon or examine grant table references: 'xl info' or 'xentop' to confirm paravirtualized I/O is in use
    Affected if The system is actively using Xen grant tables for paravirtualized device communication

A user is affected if they are running a Debian 9.0 Xen guest (or any system with Xen frontend drivers) with an unpatched kernel and have the vulnerable frontend drivers loaded and actively communicating with a Xen backend.

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
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Apply kernel patches that properly synchronize grant reference freeing with access revocation; ensure Xen hypervisor and toolstack are also updated to compatible versions to prevent backend exploitation.

Recommended fix High confidence

Debian 10/11 with updated kernel packages, or a newer supported Linux distribution with Xen PV guest support

  1. 1. Check current kernel version: uname -r
  2. 2. For Debian 9 (Stretch), note that it reached end of life in June 2022 and no longer receives security updates
  3. 3. Upgrade to a supported Debian release (Debian 10 Buster or Debian 11 Bullseye) to receive the patched kernel
  4. 4. If migrating to a newer Debian release, update /etc/apt/sources.list to point to the new release repositories
  5. 5. Run 'apt-get update' and 'apt-get dist-upgrade' to upgrade all packages including the kernel
  6. 6. Reboot the system into the new kernel: reboot
  7. 7. Verify the new kernel version is running: uname -r
  8. 8. Confirm the xenbus driver has been updated by checking the kernel version includes the fix (check CVE references in vendor security notices)
Caveat Upgrading from Debian 9 to a newer Debian release may require application compatibility testing as some older packages may have behavior changes; ensure critical applications are backed up and tested before production upgrade

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

Fix this in Debian Linux Scoped from the published advisory
  • Consultation4.0 h
  • Implementation8.0 h
  • Testing6.0 h
  • Review / QA4.0 h
22.0 hours of engineering $3,860
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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-2022-23042 in production — separate from our analysis above.

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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
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  • Version or environment caveats, and links to real fixes
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