CVE-2021-44879

System crash via special-file garbage collection

Published Feb 13, 2022 · Updated Aug 4, 2024

NULL pointer dereference in the Linux kernel before 5.16.3 allows attackers to crash a system via a crafted F2FS image. During garbage collection, gc_data_segment passes a special-file page without mapping address-space operations to move_data_page, which calls mapping->a_ops->set_dirty_page through a NULL pointer. Triggering the crash requires the crafted image to be mounted and operated on, so the consequence is limited to a system crash.

CVSS severity5.5
Medium
EPSS probability1.23%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

NULL pointer dereference in the Linux kernel before 5.16.3 allows attackers to crash a system via a crafted F2FS image. During garbage collection, gc_data_segment passes a special-file page without mapping address-space operations to move_data_page, which calls mapping->a_ops->set_dirty_page through a NULL pointer. Triggering the crash requires the crafted image to be mounted and operated on, so the consequence is limited to a system crash.

The record

CVE
CVE-2021-44879
Published
Feb 13, 2022
Updated
Aug 4, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-476, T1499
Attack vector
local
Privileges
unauthenticated

Timeline

How it unfolded

  1. Feb 13, 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

5.5NIST NVDCVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
4.3NIST NVDAV:N/AC:M/Au:N/C:N/I:N/A:P

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-476NULL Pointer Dereference
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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