dbcve.org
FedoraOperating system · Fedoraproject

CVE-2023-1386

HIGH · 7.8 CVSS v3.1 Published 2023-07-24
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
A flaw was found in the 9p passthrough filesystem (9pfs) implementation in QEMU. When a local user in the guest writes an executable file with SUID or SGID, none of these privileged bits are correctly dropped. As a result, in rare circumstances, this flaw could be used by malicious users in the guest to elevate their privileges within the guest and help a host local user to elevate privileges on the host.

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

A flaw in QEMU's 9p passthrough filesystem (9pfs) fails to drop SUID/SGID bits when guest users write executable files, allowing privilege escalation within the guest and potentially aiding host privilege escalation.

MitigationUpgrade QEMU to a version containing the fix for CVE-2023-1386, or if upgrade is not feasible, disable the 9pfs passthrough functionality if not required.

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
FedoraOperating system
Affected:= 38
QemuApplication
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
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 QEMU installation and version
    Run `qemu --version` or `rpm -q qemu` (on RHEL-based) or `dpkg -l qemu` (on Debian-based) to find the installed QEMU version
    Affected if The installed version is any version of QEMU (all versions are affected per the CVE) and the version is not yet patched
  2. Check for active 9pfs filesystem usage
    Run `ps aux | grep -E 'qemu|virt' | grep -i 9p` or inspect running VM processes for 9p filesystem mount options. Use `ls -la /proc/<pid>/mountinfo` for running QEMU processes to look for '9p' or 'virtio_9p' entries
    Affected if Any running virtual machine process has a 9p filesystem mounted with 'passthrough' or 'mapped' security model options
  3. Inspect libvirt domain XML configurations
    For libvirt-managed VMs, run `virsh list --all` to list all domains, then `virsh dumpxml <domain>` for each and search for `<filesystem type='mount' source dir='...'>`. Look for entries with `<driver type='9pfs'/>` and `<access mode='passthrough'/>`
    Affected if Any VM configuration contains a 9pfs filesystem device with passthrough access mode enabled
  4. Check for 9p kernel modules
    Run `lsmod | grep 9p` or `modinfo 9p` to see if the 9p filesystem modules are loaded or available on the host
    Affected if The 9p kernel modules are loaded and the host is being used to run VMs with 9pfs passthrough enabled
  5. Verify passthrough security model in use
    Examine the 9p mount options in `/proc/mounts` on the guest side, or inspect the libvirt XML for `<access mode='passthrough'>` or `<security model='passthrough'>`. The vulnerability specifically affects passthrough mode
    Affected if The 9pfs is configured with passthrough security model where guest file ownership and permissions directly affect host files

A user is affected if they run QEMU with any 9pfs passthrough filesystem enabled in their virtual machines, regardless of QEMU version since all versions are vulnerable.

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

Upgrade QEMU to a version containing the fix for CVE-2023-1386, or if upgrade is not feasible, disable the 9pfs passthrough functionality if not required.

Fix this in Fedora 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-2023-1386 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