CVE-2021-47359

System hang via unlocked CIFS file-list traversal

Published May 21, 2024 · Updated May 23, 2026

Improper locking in Linux CIFS 5.13.12 through 5.14.8 allows local users to hang the system through concurrent filesystem operations. The cifs_close_deferred_file function traverses an inode open-file list while locking only each deferred-close list, permitting concurrent mutation of the traversal. Triggering the defect requires local access and sustained CIFS file operations; the resulting soft lockup stalls a CPU and can hang the host.

CVSS severity5.5
Medium
EPSS probability0.16%
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 Linux CIFS 5.13.12 through 5.14.8 allows local users to hang the system through concurrent filesystem operations. The cifs_close_deferred_file function traverses an inode open-file list while locking only each deferred-close list, permitting concurrent mutation of the traversal. Triggering the defect requires local access and sustained CIFS file operations; the resulting soft lockup stalls a CPU and can hang the host.

The record

CVE
CVE-2021-47359
Published
May 21, 2024
Updated
May 23, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
CWE-667
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. May 21, 2024CVE publishedPublication date reported by the CVE source.
  2. May 23, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

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

  1. Affected versionversion=0ca6ac8a2691762307beaa4841255d1cfe6b2684
  2. Affected versionversion=5.13.12 <5.14
  3. Affected versionversion=5.14
  4. Affected versionversion=9e992755be8f2d458a0bcbefd19e493483c1dba2 <71826b068884050d5fdd37fda857ba1539c513d3
  5. Affected versionversion=9e992755be8f2d458a0bcbefd19e493483c1dba2 <9f6c7aff21f81ae8856da1f63847d1362d523409

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=0ca6ac8a2691762307beaa4841255d1cfe6b2684; version=5.13.12 <5.14; version=5.14; version=9e992755be8f2d458a0bcbefd19e493483c1dba2 <71826b068884050d5fdd37fda857ba1539c513d3; version=9e992755be8f2d458a0bcbefd19e493483c1dba2 <9f6c7aff21f81ae8856da1f63847d1362d523409

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.

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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)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-667Improper Locking

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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