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Vulnerabilities

Vulnerability · CVE-2021-47107

In the Linux kernel, the following vulnerability has been resolved: NFSD: Fix READDIR buffer overflow If a client sends a READDIR count argument that is too small (say…

Published Mar 4, 2024 · catalog updated Oct 14, 2026 · linux kernel

Check if you run it

No confirmed exploitation is on record for CVE-2021-47107. EPSS is 0.85%. Act only if a listed version of linux kernel is installed.

Gaps on this record

  • No vendor fix or required action is stored. Compare the linked advisory before you change production.
Severity
High7.8
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
0.85%
Remediation
Not established
Affected products
cpe linux/linux kernel

In the Linux kernel, the following vulnerability has been resolved: NFSD: Fix READDIR buffer overflow If a client sends a READDIR count argument that is too small (say, zero), then the buffer size calculation in the new init_dirlist helper functions results in an underflow, allowing the XDR stream functions to write beyond the actual buffer. This calculation has always been suspect. NFSD has never sanity- checked the READDIR count argument, but the old entry encoders managed the problem correctly. With the commits below, entry encoding changed, exposing the underflow to the pointer arithmetic in xdr_reserve_space(). Modern NFS clients attempt to retrieve as much data as possible for each READDIR request. Also, we have no unit tests that exercise the behavior of READDIR at the lower bound of @count values. Thus this case was missed during testing.

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

  • cpe linux/linux kernel5.16

How to fix CVE-2021-47107

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

No confirmed exploitation is on record for CVE-2021-47107. EPSS is 0.85%. Act only if a listed version of linux kernel is installed.

Which versions are affected?

Compare what you have installed with linux/linux kernel 5.16. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

CWE-120: Classic Buffer Overflow. EPSS 0.85%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Code

The project this record applies to. Exploit listings stay in References.

No public source repository is identified for this product.

Timeline

Detection, updates, and resolution for this record.

  1. Mar 4, 2024 · NIST NVD

    Detected

    In the Linux kernel, the following vulnerability has been resolved: NFSD: Fix READDIR buffer overflow If a client sends a READDIR count argument that is too small (say, zero), then the buffer size calculation in the new init_dirlist helper functions results in an underflow, allowing the XDR stream functions to write beyond the actual buffer. This calculation has always been suspect. NFSD has never

  2. Oct 14, 2026 · NIST NVD

    Updated

    In the Linux kernel, the following vulnerability has been resolved: NFSD: Fix READDIR buffer overflow If a client sends a READDIR count argument that is too small (say, zero), then the buffer size calculation in the new init_dirlist helper functions results in an underflow, allowing the XDR stream functions to write beyond the actual buffer. This calculation has always been suspect. NFSD has never

Sources

  • CVE.orgVulnerability recordCVE-2021-47107

    Official CVE identifier

    cve.org
  • FIRST EPSSExploitation probabilityCVE-2021-47107

    30-day exploitation probability 0.8%

    first.org
  • NIST NVDVulnerability recordCVE-2021-47107

    In the Linux kernel, the following vulnerability has been resolved: NFSD: Fix READDIR buffer overflow If a client sends a READDIR count argument that is too small (say, zero), then the buffer size calculation in the new init_dirlist helper functions results in an underflow, all

    nvd.nist.gov

References

Freshness

Last verified in this catalog Oct 16, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.