CVE-2021-47316

nfsd: fix NULL dereference in nfs3svc_encode_getaclres

MEDIUM
5.5
CVSS Score
Published: May 21, 2024 at 02:35 PM UTC
Updated: October 14, 2026 at 01:17 PM UTC
2 products affected across 2 vendorsLinux KernelSIMATIC S7-1500 TM MFP

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Severity
MEDIUM5.5
Exploit prediction
EPSS 0.6%
SSVC
No known exploit

Description

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

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

5.13 ≤ v < 5.13.420798dfe249a01ad1b12eec7dbc572db5003244a5.13d505e66191072748620fc0af038cea4e4da0e3cd
Vendor states this is fixed in 650e6f383a6eb40f7c0a010982a74ab4b6893870 (fixed)
Vendor states this is fixed in ab1016d39cc052064e32f25ad18ef8767a0ee3b8 (fixed)
Vendor states this is fixed in e79057d15d96ef19de4de6d7e479bae3d58a2a8d (fixed)
Vendor states this is fixed in 5.13 (unaffected)
Vendor states this is fixed in 5.13.4 (unaffected)
Vendor states this is fixed in 5.14 (unaffected)

References (5)

Patch
Source: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
https://git.kernel.org/stable/c/650e6f383a6eb40f7c0a010982a74ab4b6893870
Patch
Source: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
https://git.kernel.org/stable/c/ab1016d39cc052064e32f25ad18ef8767a0ee3b8
Patch
Source: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
https://git.kernel.org/stable/c/e79057d15d96ef19de4de6d7e479bae3d58a2a8d
Source: 0b142b55-0307-4c5a-b3c9-f314f3fb7c5e
https://cert-portal.siemens.com/productcert/html/ssa-265688.html
Source: 0b142b55-0307-4c5a-b3c9-f314f3fb7c5e
https://cert-portal.siemens.com/productcert/html/ssa-355557.html

SSVC — Action Prioritization

SSVCNo known exploitNot automatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

Attack Vector
LOCAL
Complexity
LOW
Privileges
LOW
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
NONE
Integrity
NONE
Availability
HIGH
Vector?

Quick Info

StatusMODIFIED
CWE
CWE-476

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