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Debian LinuxOperating system · Debian

CVE-2022-23039

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

The gntalloc driver in Linux PV frontends has a race condition vulnerability in grant table handling. The driver checks whether a grant reference is still in use before removing access, but assumes the removal will succeed without verification. A malicious backend can map the granted page between the check and removal operations, allowing it to retain access to guest memory pages after I/O completion, leading to potential data leaks, corruption, or DoS.

MitigationApply the upstream kernel patches that add proper synchronization and verify successful removal of granted access. In the meantime, ensure only trusted Xen backends are used in the environment, as this attack requires a malicious or compromised backend.

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. Identify if the system is a Xen paravirtualized guest
    Run 'xl list' or 'xm list' to list running Xen VMs, or check dmesg for 'Xen' mentions with 'dmesg | grep -i xen'. On Linux guests, check /proc/xen for existence.
    Affected if The system is running as a Xen PV guest and the gntalloc driver is in use
  2. Check if the gntalloc driver is loaded
    Run 'lsmod | grep gntalloc' to see if the gntalloc kernel module is currently loaded.
    Affected if The gntalloc module is loaded in a Xen PV guest environment
  3. Determine the kernel version for patch status
    Run 'uname -r' to get the kernel version, then cross-reference with vendor security advisories for CVE-2022-23039 patch information.
    Affected if The kernel is an unpatched version and the system is a Xen PV guest using grant tables
  4. Identify active grant table references
    Check /dev/gntalloc device usage if present (ls -la /dev/gntalloc), and review any guest configurations using grant table passthrough.
    Affected if Grant table devices are accessible and in use by the guest
  5. Audit backend trust status in the Xen environment
    Review Xen configuration files in /etc/xen/ and check pool/host configurations for backend VM sources. Inspect xl cfg files for 'backend' or ' vif' entries.
    Affected if The environment contains untrusted or unknown Xen backends providing grant table access

A system is affected if it runs as a Xen PV guest with the gntalloc driver loaded and grant tables active, particularly when connecting to untrusted Xen backends.

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 the upstream kernel patches that add proper synchronization and verify successful removal of granted access. In the meantime, ensure only trusted Xen backends are used in the environment, as this attack requires a malicious or compromised backend.

Recommended fix Moderate confidence

Debian 9.0 (stretch) should be upgraded to Debian 10 (buster) or later, which includes the patched kernel with the gntalloc race condition fix; alternatively, apply the upstream Linux kernel patch for CVE-2022-23039 to version 5.10.19 or later

  1. 1. Identify the current kernel version running in the Debian 9.0 system using 'uname -r'
  2. 2. Update the package repository lists using 'apt-get update'
  3. 3. Upgrade the Linux kernel to the latest available version that includes the fix for CVE-2022-23039 using 'apt-get install linux-image-generic' or 'apt-get dist-upgrade'
  4. 4. Reboot the system to load the new kernel using 'reboot'
  5. 5. After reboot, verify the new kernel version is running using 'uname -r' and confirm it includes the gntalloc driver fix
Caveat Kernel upgrades may require system reboot and could introduce compatibility issues with custom kernel modules or older software dependencies; Xen environments may need coordination between host and guest updates

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

Fix this in Debian Linux Scoped from the published advisory
  • Consultation3.0 h
  • Implementation8.0 h
  • Testing6.0 h
  • Review / QA3.0 h
20.0 hours of engineering $3,480
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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-2022-23039 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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