CVE-2021-47041Network attack vector

Kernel hang via incorrect state-change callback locking

Published Feb 28, 2024 · Updated Aug 5, 2026

Improper locking in affected Linux kernel versions allows remote attackers to hang co-located NVMe/TCP host-and-target systems. The nvmet_tcp_state_change callback takes write_lock_bh even though it does not modify TCP state, creating a lock inversion with the host-side callback. The hang requires nvmet-tcp and nvme-tcp on the same system and is reachable before authentication by opening and closing a listening target connection.

CVSS severity5.5
Medium
EPSS probability0.49%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper locking in affected Linux kernel versions allows remote attackers to hang co-located NVMe/TCP host-and-target systems. The nvmet_tcp_state_change callback takes write_lock_bh even though it does not modify TCP state, creating a lock inversion with the host-side callback. The hang requires nvmet-tcp and nvme-tcp on the same system and is reachable before authentication by opening and closing a listening target connection.

The record

CVE
CVE-2021-47041
Published
Feb 28, 2024
Updated
Aug 5, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
CWE-667, T1499
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Feb 28, 2024CVE publishedPublication date reported by the CVE source.
  2. Aug 5, 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=5.0
  2. Affected versionversion=872d26a391da92ed8f0c0f5cb5fef428067b7f30 <06beaa1a9f6e501213195e47c30416032fd2bbd5
  3. Affected versionversion=872d26a391da92ed8f0c0f5cb5fef428067b7f30 <60ade0d56b06537a28884745059b3801c78e03bc
  4. Affected versionversion=872d26a391da92ed8f0c0f5cb5fef428067b7f30 <906c538340dde6d891df89fe7dac8eaa724e40da
  5. Affected versionversion=872d26a391da92ed8f0c0f5cb5fef428067b7f30 <999d606a820c36ae9b9e9611360c8b3d8d4bb777
  6. Affected versionversion=872d26a391da92ed8f0c0f5cb5fef428067b7f30 <b5332a9f3f3d884a1b646ce155e664cc558c1722

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=5.0; version=872d26a391da92ed8f0c0f5cb5fef428067b7f30 <06beaa1a9f6e501213195e47c30416032fd2bbd5; version=872d26a391da92ed8f0c0f5cb5fef428067b7f30 <60ade0d56b06537a28884745059b3801c78e03bc; version=872d26a391da92ed8f0c0f5cb5fef428067b7f30 <906c538340dde6d891df89fe7dac8eaa724e40da; version=872d26a391da92ed8f0c0f5cb5fef428067b7f30 <999d606a820c36ae9b9e9611360c8b3d8d4bb777; version=872d26a391da92ed8f0c0f5cb5fef428067b7f30 <b5332a9f3f3d884a1b646ce155e664cc558c1722

Published CVSS scores

5.5NIST NVDCVSS:3.1/AV:L/AC:L/PR:L/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-667Improper Locking
T1499Endpoint Denial of Service

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

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Your stack

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