---
id: CVE-2021-47316
title: |-
  In the Linux kernel, the following vulnerability has been resolved:

  nfsd: fix NULL dereference in nfs3svc_encode_getaclres

  In error cases the dentry may be NULL.

  Before 20798dfe249a, the encoder also checked dentry and
  d_really_is_pos…
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  nfsd: fix NULL dereference in nfs3svc_encode_getaclres

  In error cases the dentry may be NULL.

  Before 20798dfe249a, the encoder also checked dentry and
  d_really_is_pos…
severity: high
cvss: 7.5
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H'
cwe:
  - CWE-476
vendor: linux
product: linux_kernel
affected:
  - 'linux_kernel >= 5.13, < 5.13.4'
patched:
  - linux_kernel 5.13.4
published: '2024-05-21'
updated: '2026-10-14'
sourceUpdated: '2026-10-14T13:17:13.620'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2021-47316'
references:
  - url: 'https://git.kernel.org/stable/c/650e6f383a6eb40f7c0a010982a74ab4b6893870'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/ab1016d39cc052064e32f25ad18ef8767a0ee3b8'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/e79057d15d96ef19de4de6d7e479bae3d58a2a8d'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/650e6f383a6eb40f7c0a010982a74ab4b6893870'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'https://git.kernel.org/stable/c/ab1016d39cc052064e32f25ad18ef8767a0ee3b8'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'https://git.kernel.org/stable/c/e79057d15d96ef19de4de6d7e479bae3d58a2a8d'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'https://cert-portal.siemens.com/productcert/html/ssa-265688.html'
    label: 0b142b55-0307-4c5a-b3c9-f314f3fb7c5e
  - url: 'https://cert-portal.siemens.com/productcert/html/ssa-355557.html'
    label: 0b142b55-0307-4c5a-b3c9-f314f3fb7c5e
tags:
  - nvd
  - cve.org
epss: 0.00622
epssPercentile: 0.49616
ingestedAt: '2026-10-14T13:30:58.420Z'
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: partial
  timestamp: '2024-05-21T18:45:04.809482Z'
---

## Overview

In the Linux kernel, the following vulnerability has been resolved:

nfsd: fix NULL dereference in nfs3svc_encode_getaclres

In error cases the dentry may be NULL.

Before 20798dfe249a, the encoder also checked dentry and
d_really_is_positive(dentry), but that looks like overkill to me--zero
status should be enough to guarantee a positive dentry.

This isn't the first time we've seen an error-case NULL dereference
hidden in the initialization of a local variable in an xdr encoder.  But
I went back through the other recent rewrites and didn't spot any
similar bugs.

## Affected

- `linux_kernel >= 5.13, < 5.13.4`

## Remediation

Upgrade past the affected range:

- `linux_kernel 5.13.4`