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Debian LinuxOperating system · Debian

CVE-2022-42332

HIGH · 7.8 CVSS v3.1 Published 2023-03-21
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
80/100
Remediation priority · High
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
x86 shadow plus log-dirty mode use-after-free In environments where host assisted address translation is necessary but Hardware Assisted Paging (HAP) is unavailable, Xen will run guests in so called shadow mode. Shadow mode maintains a pool of memory used for both shadow page tables as well as auxiliary data structures. To migrate or snapshot guests, Xen additionally runs them in so called log-dirty mode. The data structures needed by the log-dirty tracking are part of aformentioned auxiliary data. In order to keep error handling efforts within reasonable bounds, for operations which may require memory allocations shadow mode logic ensures up front that enough memory is available for the worst case requirements. Unfortunately, while page table memory is properly accounted for on the code path requiring the potential establishing of new shadows, demands by the log-dirty infrastructure were not taken into consideration. As a result, just established shadow page tables could be freed again immediately, while other code is still accessing them on the assumption that they would remain allocated.

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

In Xen hypervisor environments using shadow mode (when Hardware Assisted Paging is unavailable), a use-after-free vulnerability exists in the log-dirty infrastructure. The memory accounting logic properly reserves memory for shadow page tables but fails to account for log-dirty mode memory requirements, causing newly allocated shadow page tables to be freed while other code still holds references to them.

MitigationApply the Xen security patch for CVE-2022-42332. If unable to patch immediately, avoid running guests in shadow mode with log-dirty operations (migration/snapshots) until the update can be applied.

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:= 11.0
FedoraOperating system
Affected:= 37= 38
XenOperating system
Affected:>= 3.2.0

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
High
Integrity
High
Availability
High

CVSS:3.1/AV:L/AC:L/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 Xen hypervisor version
    Run `xl version` or `xm version` to confirm the installed Xen version, or check the system package manager for the xen-hypervisor package version
    Affected if The installed Xen version is 3.2.0 or higher and matches the affected product versions (Debian 11.0, Fedora 37-38)
  2. Confirm shadow mode is enabled for guest domains
    Examine guest domain configuration files in /etc/xen/ or via `xl list -l` to identify domains configured with 'shadow_mode' or 'hap' set to 0 (disabled), which forces shadow paging
    Affected if Any guest domains are configured to use shadow mode instead of Hardware Assisted Paging (HAP)
  3. Detect active or recent log-dirty operations
    Check for ongoing domain migrations or snapshot operations using `xl list`, `xl migrate`, or system logs for log-dirty related activity. Log-dirty mode is used during live migration and snapshot operations
    Affected if Guest domains using shadow mode are performing live migrations or snapshots, which trigger log-dirty memory operations
  4. Verify log-dirty memory allocation exists
    Monitor domain memory allocation during migration/snapshot activities via `xl top` or xenstat tools to observe if shadow page structures are being allocated
    Affected if Shadow page tables are being allocated for domains in shadow mode while log-dirty operations are active, creating the condition for use-after-free

A system is affected if it runs Xen >= 3.2.0 with guest domains configured to use shadow mode (HAP disabled) while performing log-dirty operations such as live migration or snapshots.

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.

From vendor data
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Apply the Xen security patch for CVE-2022-42332. If unable to patch immediately, avoid running guests in shadow mode with log-dirty operations (migration/snapshots) until the update can be applied.

Fix this in Debian Linux Scoped from the published advisory
  • Consultation4.0 h
  • Implementation8.0 h
  • Testing12.0 h
  • Review / QA4.0 h
28.0 hours of engineering $4,760
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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-2022-42332 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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