CVE-2021-45868

Kernel crash via unchecked quota block number

Published Mar 18, 2022 · Updated Aug 4, 2024

Use-after-free in the Linux kernel before 5.15.3 allows local users to crash the kernel by supplying a corrupted on-disk quota file. fs/quota/quota_tree.c accepts a quota-tree block number that is not smaller than dqi_blocks, allowing allocation of an already allocated block and creating a tree loop. Triggering the fault requires local interaction with a corrupted quota file; the demonstrated consequence is a kernel oops and service interruption.

CVSS severity5.5
Medium
EPSS probability1.34%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Use-after-free in the Linux kernel before 5.15.3 allows local users to crash the kernel by supplying a corrupted on-disk quota file. fs/quota/quota_tree.c accepts a quota-tree block number that is not smaller than dqi_blocks, allowing allocation of an already allocated block and creating a tree loop. Triggering the fault requires local interaction with a corrupted quota file; the demonstrated consequence is a kernel oops and service interruption.

The record

CVE
CVE-2021-45868
Published
Mar 18, 2022
Updated
Aug 4, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-416, T1499
Attack vector
local
Privileges
unauthenticated

Timeline

How it unfolded

  1. Mar 18, 2022CVE 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 vectorlocal
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

4.3NIST NVDAV:N/AC:M/Au:N/C:N/I:N/A:P
5.5NIST NVDCVSS:3.1/AV:L/AC:L/PR:N/UI:R/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 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-416Use After Free
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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