CVE-2021-38201Network attack vector

Service interruption via NFS READ_PLUS page-array overrun

Published Aug 8, 2021 · Updated Aug 4, 2024

Out-of-bounds memory access in the Linux kernel before 5.13.4 allows remote attackers to interrupt service through NFS 4.2 READ_PLUS requests. In net/sunrpc/xdr.c, xdr_set_page_base() clamps an offset at the end of page data and then dereferences xdr->buf->pages beyond the allocated page array instead of returning to tail-buffer handling. Unauthenticated network access to an NFS 4.2 service and repeated READ_PLUS operations are required; the reported consequence is service interruption.

CVSS severity7.5
High
EPSS probability3.36%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Out-of-bounds memory access in the Linux kernel before 5.13.4 allows remote attackers to interrupt service through NFS 4.2 READ_PLUS requests. In net/sunrpc/xdr.c, xdr_set_page_base() clamps an offset at the end of page data and then dereferences xdr->buf->pages beyond the allocated page array instead of returning to tail-buffer handling. Unauthenticated network access to an NFS 4.2 service and repeated READ_PLUS operations are required; the reported consequence is service interruption.

The record

CVE
CVE-2021-38201
Published
Aug 8, 2021
Updated
Aug 4, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-119, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 8, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 4, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

5.0NIST NVDAV:N/AC:L/Au:N/C:N/I:N/A:P
7.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-119Improper Restriction of Operations within the Bounds of a Memory Buffer
T1499.004Application or System Exploitation

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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