dbcve.org
FreeBSDOperating system

CVE-2022-23092

HIGH · 8.8 CVSS v3.1 Published 2024-02-15
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
95/100
Remediation priority · Urgent
Remotely reachable No privileges

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
The implementation of lib9p's handling of RWALK messages was missing a bounds check needed when unpacking the message contents. The missing check means that the receipt of a specially crafted message will cause lib9p to overwrite unrelated memory. The bug can be triggered by a malicious bhyve guest kernel to overwrite memory in the bhyve(8) process. This could potentially lead to user-mode code execution on the host, subject to bhyve's Capsicum sandbox.

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 · moderate confidence

A missing bounds check in lib9p's RWALK message unpacking allows a malicious bhyve guest kernel to send specially crafted messages that overwrite memory in the bhyve process, potentially enabling user-mode code execution on the host despite Capsicum sandboxing.

MitigationUpdate lib9p to include proper bounds validation in RWALK message handling; review and test the fix within the bhyve context to verify the memory corruption is prevented.

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
FreeBSDOperating system
Affected:= 13.0= 13.1

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
Network
Complexity
Low
Privileges
None
User interaction
Required
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/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 FreeBSD version
    Run 'freebsd-version -k' or 'uname -r' to determine the running kernel version
    Affected if Version is 13.0 or 13.1
  2. Verify bhyve is installed
    Run 'which bhyve' or check if bhyve binary exists at /usr/sbin/bhyve
    Affected if bhyve is installed on the system
  3. Determine if 9p filesystem sharing is in use
    Inspect running bhyve VM configurations or active VM instances for '-s <slot>,virtio-9p,<share>' or similar 9p device arguments indicating 9p filesystem sharing is enabled
    Affected if A bhyve VM is configured with virtio-9p (9p filesystem) sharing enabled
  4. Check lib9p library version
    Run 'pkg info lib9p' or check /usr/local/lib/lib9p* for the installed lib9p library version if present
    Affected if lib9p version corresponds to the base system version (13.0 or 13.1) and 9p sharing is active
  5. Inspect active bhyve processes
    Use 'ps aux' or 'procstat -a' to list all running bhyve processes and verify if any are using 9p exports
    Affected if Any bhyve process is actively using 9p filesystem exports from the guest

A system is affected if it runs FreeBSD 13.0 or 13.1 with bhyve and has a VM configured to use virtio-9p filesystem sharing, enabling a malicious guest to trigger the unbounded memory write in lib9p's RWALK handler.

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

Update lib9p to include proper bounds validation in RWALK message handling; review and test the fix within the bhyve context to verify the memory corruption is prevented.

Recommended fix Moderate confidence

FreeBSD 13.1-RELEASE or later (or apply security patch from FreeBSD SA-22_02.lib9p)

  1. Run `freebsd-update fetch` to retrieve the latest security updates
  2. Run `freebsd-update install` to apply the updates
  3. Reboot the system if necessary for kernel updates
  4. Verify the update was applied by checking the FreeBSD security advisory for this CVE
Caveat Standard FreeBSD update risks - ensure backups exist before updating production systems

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

Fix this in FreeBSD 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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Scan for this in your stack

Free · runs locally
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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-2022-23092 in production — separate from our analysis above.

No notes yet

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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
  • 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