CVE-2021-47316 nfsd: fix NULL dereference in nfs3svc_encode_getaclres

What is CVE-2021-47316?

CVE-2021-47316 is a high-severity vulnerability in Linux kernel, published on 21 May 2024. An attacker can exploit it over the internet without logging in, with no action from the victim.

Official 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.

Weakness: CWE-476

Which versions are affected by CVE-2021-47316?

It affects 1 product.

Products include Linux kernel.

How do I fix CVE-2021-47316?

No fix has been published for CVE-2021-47316 yet. Limit exposure of the affected software until one is available.

Is CVE-2021-47316 being exploited?

There is no known exploitation of CVE-2021-47316 in the wild and no public exploit code.

Other vulnerabilities in Linux kernel

• CVE-2026-53266 Linux Kernel Out-of-Bounds Write Exploited High 8.8
• CVE-2013-6282 Linux Kernel Improper Input Validation Exploited High 8.8
• CVE-2022-0185 Linux Kernel Heap-Based Buffer Overflow Exploited High 8.4
• CVE-2013-2094 Linux Kernel Privilege Escalation Exploited High 8.4
• CVE-2026-53362 Linux Kernel Unspecified Exploited High 7.8

All Linux kernel vulnerabilities

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as GHSA-x95x-w6hq-mwxc, UBUNTU-CVE-2021-47316.