CVE-2021-47241Network attack vector

Kernel warning via ethtool length undercount

Published May 21, 2024 · Updated May 11, 2026

Message-length miscalculation in the Linux kernel allows attackers to trigger a kernel warning through an ethtool string-set request. The reply-size calculation in net/ethtool/strset.c omits the outer ETHTOOL_A_STRSET_STRINGSETS nest while allocating the netlink response. The warning requires an unrounded buffer size, a per-device string set, and a device name of at least 12 characters; current user space reaches it when reading private flags.

CVSS severity7.5
High
EPSS probability1.02%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

Message-length miscalculation in the Linux kernel allows attackers to trigger a kernel warning through an ethtool string-set request. The reply-size calculation in net/ethtool/strset.c omits the outer ETHTOOL_A_STRSET_STRINGSETS nest while allocating the netlink response. The warning requires an unrounded buffer size, a per-device string set, and a device name of at least 12 characters; current user space reaches it when reading private flags.

The record

CVE
CVE-2021-47241
Published
May 21, 2024
Updated
May 11, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
CWE-266
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 21, 2024CVE publishedPublication date reported by the CVE source.
  2. May 11, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=5.6
  2. Affected versionversion=71921690f9745fef60a2bad425f30adf8cdc9da0 <cfc7f0e70d649e6d2233fba0d9390b525677d971
  3. Affected versionversion=71921690f9745fef60a2bad425f30adf8cdc9da0 <e175aef902697826d344ce3a12189329848fe898
  4. Affected versionversion=71921690f9745fef60a2bad425f30adf8cdc9da0 <fb3a948143688e14e2cfd2a2812877923d0e5e92

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=5.6; version=71921690f9745fef60a2bad425f30adf8cdc9da0 <cfc7f0e70d649e6d2233fba0d9390b525677d971; version=71921690f9745fef60a2bad425f30adf8cdc9da0 <e175aef902697826d344ce3a12189329848fe898; version=71921690f9745fef60a2bad425f30adf8cdc9da0 <fb3a948143688e14e2cfd2a2812877923d0e5e92
The Linux Kernel Organization · Linux Kernelversion=5.6; version=71921690f974 <cfc7f0e70d64; version=71921690f974 <e175aef90269; version=71921690f974 <fb3a94814368

Published CVSS scores

7.5CISA-ADPCVSS: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.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

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-266Incorrect Privilege Assignment

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo