CVE-2021-47584

Kernel crash via zero post-donation hweight

Published Jun 19, 2024 · Updated May 11, 2026

Divide by zero in Linux 5.10 through 5.10.87 and 5.11 through 5.15.10 allows local users to crash the kernel via iocost. The blk-iocost transfer_surpluses logic lets a cgroup with active hweight 1 donate its only weight, then divides using the resulting zero after-donation weight. Triggering the condition requires local low-privileged cgroup activity under the iocost controller and causes a kernel oops that interrupts the host.

CVSS severity5.5
Medium
EPSS probability0.25%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Divide by zero in Linux 5.10 through 5.10.87 and 5.11 through 5.15.10 allows local users to crash the kernel via iocost. The blk-iocost transfer_surpluses logic lets a cgroup with active hweight 1 donate its only weight, then divides using the resulting zero after-donation weight. Triggering the condition requires local low-privileged cgroup activity under the iocost controller and causes a kernel oops that interrupts the host.

The record

CVE
CVE-2021-47584
Published
Jun 19, 2024
Updated
May 11, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
CWE-369, T1499.004
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Jun 19, 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

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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=5.10
  2. Affected versionversion=f1de2439ec43b74764f2a26e3a310b24407e3bde <3a1a4eb574178c21241a6200f4785572e661c472
  3. Affected versionversion=f1de2439ec43b74764f2a26e3a310b24407e3bde <a7c80674538f15f85d68138240aae440b8039519
  4. Affected versionversion=f1de2439ec43b74764f2a26e3a310b24407e3bde <edaa26334c117a584add6053f48d63a988d25a6e

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=5.10; version=f1de2439ec43b74764f2a26e3a310b24407e3bde <3a1a4eb574178c21241a6200f4785572e661c472; version=f1de2439ec43b74764f2a26e3a310b24407e3bde <a7c80674538f15f85d68138240aae440b8039519; version=f1de2439ec43b74764f2a26e3a310b24407e3bde <edaa26334c117a584add6053f48d63a988d25a6e

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-369Divide By Zero
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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