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CVE Record

CVE-2023-53680: NFSD: Avoid calling OPDESC() with ops->opnum == OP_ILLEGAL

In the Linux kernel, the following vulnerability has been resolved: NFSD: Avoid calling OPDESC() with ops->opnum == OP_ILLEGAL OPDESC() simply indexes into nfsd4_ops[] by the op's operation number, without range checking that value. It assumes callers are careful to avoid calling it with an out-of-bounds opnum value. nfsd4_decode_compound() is not so careful, and can invoke OPDESC() with opnum set to OP_ILLEGAL, which is 10044 -- well beyond the end of nfsd4_ops[].

UnknownCVSS not scoredNot KEV-listedUpdated
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Glexia's TakeAutomated analysisunknown

Security readout for executives and security teams

Plain-English summary

This is a Linux kernel NFSD issue in the NFSv4 server code. A malformed or unexpected operation number can cause kernel code to index past the valid operations table. The source does not state impact, severity, or confirmed exploitation, so urgency depends on whether affected systems run reachable NFS server services.

Executive priority

Prioritize exposed NFS servers first. Treat this as patch-management important, but avoid emergency claims unless vendor impact guidance or exploitation evidence emerges.

Technical view

NFSD’s nfsd4_decode_compound() can call OPDESC() when ops->opnum is OP_ILLEGAL. OPDESC() indexes nfsd4_ops[] without range checking, and OP_ILLEGAL is far beyond that array. Stable Linux kernel commits are referenced as fixes, but the bundle provides no CVSS, CWE, or impact classification.

Likely exposure

Likely limited to Linux systems running affected kernel versions with NFSD/NFSv4 server functionality enabled, especially where NFS is reachable beyond trusted networks.

Exploitation context

The bundle marks KEV as false and provides no cited evidence of active exploitation, public exploit use, or weaponization.

Researcher notes

The core issue is unchecked array indexing through OPDESC() after an illegal NFSv4 operation number is assigned. The source identifies fixed stable commits but does not define practical impact, crashability, privilege implications, or exploit preconditions beyond the NFSD decode path.

Mitigation direction

  • Apply vendor Linux kernel updates containing the referenced stable NFSD fixes.
  • Disable NFS server functionality where it is not required.
  • Restrict NFS access to trusted networks and authenticated clients.
  • Review Linux distribution advisories for branch-specific fixed package versions.

Validation and detection

  • Inventory systems running Linux kernels in the affected version ranges.
  • Identify hosts with NFSD or NFSv4 server roles enabled.
  • Confirm whether vendor kernel packages include the referenced stable fixes.
  • Check whether NFS services are exposed outside trusted administrative networks.
Prepared
Confidence
medium
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

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CVE-2023-53680 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
0ADP providers
6Source links

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.

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
LinuxLinuxf4f9ef4a1b0a1ca80b152e28e176d69515bdf7e8, f4f9ef4a1b0a1ca80b152e28e176d69515bdf7e8, f4f9ef4a1b0a1ca80b152e28e176d69515bdf7e8, f4f9ef4a1b0a1ca80b152e28e176d69515bdf7e8, f4f9ef4a1b0a1ca80b152e28e176d69515bdf7e8unaffected
LinuxLinux4.14, 0, 5.10.220, 5.15.107, 6.1.24, 6.2.11, 6.3affected
Weakness

CWE details

No CWE listed

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