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CVE Record

CVE-2023-53381: NFSD: fix leaked reference count of nfsd4_ssc_umount_item

In the Linux kernel, the following vulnerability has been resolved: NFSD: fix leaked reference count of nfsd4_ssc_umount_item The reference count of nfsd4_ssc_umount_item is not decremented on error conditions. This prevents the laundromat from unmounting the vfsmount of the source file. This patch decrements the reference count of nfsd4_ssc_umount_item on error.

MediumCVSS 5.5Not KEV-listedUpdated
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Glexia's TakeAutomated analysismoderate

Security readout for executives and security teams

Plain-English summary

CVE-2023-53381 is a Linux kernel NFSD bug where an internal reference count is not released during error handling. Over time, this can prevent cleanup of a mounted source file and cause availability problems. The published severity is medium, and the CVSS vector requires local low-privileged access.

Executive priority

Treat as a routine but important availability fix for Linux NFS server environments. It is not presented as remotely exploitable or actively exploited in the supplied sources, but affected infrastructure should receive normal kernel update priority.

Technical view

The flaw is in Linux kernel NFSD handling of nfsd4_ssc_umount_item. On error paths, its reference count is not decremented, preventing the laundromat from unmounting the source file vfsmount. CVSS 3.1 is 5.5: local attack vector, low complexity, low privileges, no user interaction, availability impact only.

Likely exposure

Exposure primarily concerns Linux systems running affected kernel versions with NFSD code present. It is most relevant to hosts using the kernel NFS server. Distribution backports may change exposure, so kernel package advisories are more reliable than upstream version strings alone.

Exploitation context

The source bundle does not indicate active exploitation, and CISA KEV status is false. The CVSS vector describes local, low-privileged exploitation with availability impact. No public exploit details are provided in the supplied sources.

Researcher notes

The issue is a reference leak on NFSD error handling for nfsd4_ssc_umount_item. Impact is availability through failed vfsmount cleanup. The record names upstream stable commits, but distro-specific fixed versions and backport status require vendor confirmation.

Mitigation direction

  • Update to a vendor kernel that includes the referenced upstream stable fixes.
  • Check Linux distribution advisories for backported fixes matching CVE-2023-53381.
  • Prioritize NFS server hosts and shared infrastructure where availability matters.
  • If immediate patching is not possible, review vendor guidance for supported mitigations.

Validation and detection

  • Inventory Linux kernel versions across servers and appliances.
  • Identify systems running or configured for kernel NFSD/NFS server functionality.
  • Confirm vendor kernel packages include one of the referenced stable commits or equivalent backport.
  • After patching, verify the running kernel is the updated version.
  • Track distribution security advisories for corrected package names and release status.
Prepared
Confidence
high
Sources
7

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.

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CVE-2023-53381 mapping review

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Vulnerability profileCVE Program record
Severity
Medium
CVSS
5.5 (3.1)
Known Exploited
No
Published

Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

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.

1CVSS vectors
3Timeline events
1ADP providers
6Source links

SSVC decision data

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

CVSS vector scores

1 official score

We collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.

ScoreVersionSeverityVectorExploitImpactSource
5.5CVSS 3.1MediumCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H1.83.6CISA-ADP

Vulnerability scoring details

Base CVSS 3.1 score

5.5Medium
CVSS 3.1 vector shape for CVE-2023-53381Attack VectorAttack ComplexityPrivileges RequiredUser InteractionScopeConfidentiality ImpactIntegrity ImpactAvailability Impact

Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Attack Vector
NetworkAdjacentLocalPhysical
Attack Complexity
LowHigh
Privileges Required
NoneLowHigh
User Interaction
NoneRequired
Scope
ChangedUnchanged
Confidentiality Impact
HighLowNone
Integrity Impact
HighLowNone
Availability Impact
HighLowNone

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
cvssV3_1other:ssvc

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
LinuxLinuxa4bc287943f5695209ff36bdc89f17b48d68fae7, f4e44b393389c77958f7c58bf4415032b4cda15b, f4e44b393389c77958f7c58bf4415032b4cda15b, f4e44b393389c77958f7c58bf4415032b4cda15b, f4e44b393389c77958f7c58bf4415032b4cda15bunaffected
LinuxLinux5.14, 0, 5.15.154, 6.1.16, 6.2.3, 6.3affected
Weakness

CWE details

No CWE listed

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