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CVE Record

CVE-2023-52837: nbd: fix uaf in nbd_open

In the Linux kernel, the following vulnerability has been resolved: nbd: fix uaf in nbd_open Commit 4af5f2e03013 ("nbd: use blk_mq_alloc_disk and blk_cleanup_disk") cleans up disk by blk_cleanup_disk() and it won't set disk->private_data as NULL as before. UAF may be triggered in nbd_open() if someone tries to open nbd device right after nbd_put() since nbd has been free in nbd_dev_remove(). Fix this by implementing ->free_disk and free private data in it.

UnknownCVSS not scoredNot KEV-listedUpdated
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Glexia's TakeAutomated analysisunknown

Security readout for executives and security teams

Plain-English summary

CVE-2023-52837 is a Linux kernel bug in the Network Block Device subsystem. Under a narrow timing condition, opening an NBD device after related cleanup may use already-freed memory. Public sources show kernel fixes exist, but no CVSS score or active exploitation evidence is provided.

Executive priority

Treat as a targeted kernel maintenance item, not an emergency based on current evidence. Prioritize patching where NBD is used, on shared infrastructure, or on systems with strict availability and isolation requirements.

Technical view

The issue is a use-after-free in nbd_open(). After commit 4af5f2e03013, blk_cleanup_disk() no longer clears disk->private_data. If an NBD device is opened soon after nbd_put() and nbd_dev_remove() frees the nbd structure, stale private_data may be dereferenced. The kernel fix moves private data release into ->free_disk.

Likely exposure

Exposure is limited to Linux systems running affected kernel versions where the NBD subsystem is present or used. The source record lists Linux as affected and references stable kernel fixes. Distribution-specific affected package versions are not provided in the bundle.

Exploitation context

The CVE record describes a race-like use-after-free condition in kernel NBD device handling. The provided sources do not state remote exploitability, privilege requirements, impact severity, public exploit availability, or active exploitation. CISA KEV status is false in the supplied data.

Researcher notes

Evidence is limited to the CVE record and upstream stable commit references. No CVSS, CWE, exploit status, or distro mapping is included. Avoid assuming exploitability beyond the documented UAF in nbd_open() until vendor advisories or further analysis clarify impact.

Mitigation direction

  • Update to a vendor-supported kernel that includes the referenced NBD fixes.
  • Review distribution advisories for exact fixed package versions.
  • Prioritize systems using NBD or exposing NBD functionality.
  • If no vendor package is available, track the upstream stable commits.

Validation and detection

  • Inventory Linux kernel versions across servers and appliances.
  • Identify systems using the nbd driver or NBD devices.
  • Compare deployed kernels with vendor fixed versions or referenced stable commits.
  • Confirm patched kernels are running after maintenance reboots.
Prepared
Confidence
medium
Sources
6

Public sources used

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

Conservative CVE-to-ATT&CK context

These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.

ATT&CK lookup starting points

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CVE-2023-52837 mapping review

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Vulnerability profileCVE Program record
Severity
Unknown
CVSS
Not scored
Known Exploited
No
Published
Official CVE source material

CNA and ADP enrichment extracted from CVE v5

These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.

0CVSS vectors
3Timeline events
2ADP providers
5Source links

SSVC decision data

CISA-ADPCISA Coordinator
Timestamp
Version
2.0.3
Exploitation: noneAutomatable: noTechnical Impact: partial

Vulnerability timeline

Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.

  1. CVE reservedCVE Program

    The CVE ID was reserved by the assigning CNA.

  2. CVE publishedCVE Program

    The CVE record was published.

  3. CVE updatedCVE Program

    The CVE record metadata indicates this as the latest update time.

ADP provider summaries

CISA-ADPCISA ADP Vulnrichment
other:ssvc
CVECVE Program Container

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
LinuxLinux4af5f2e0301311f88c420fcfc5f3c8611ade20ac, 4af5f2e0301311f88c420fcfc5f3c8611ade20ac, 4af5f2e0301311f88c420fcfc5f3c8611ade20ac, 4af5f2e0301311f88c420fcfc5f3c8611ade20acunaffected
LinuxLinux5.14, 0, 6.1.63, 6.5.12, 6.6.2, 6.7affected
Weakness

CWE details

No CWE listed

CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.