CVE-2021-46989

File data loss via unconditional extent-record removal

Published Feb 28, 2024 · Updated Aug 5, 2026

Data corruption in the Linux kernel HFS+ driver allows local users to lose file data by shrinking a fragmented file on a writable HFS+ volume. hfsplus_file_truncate() unconditionally removes the final overflow extent record instead of freeing only extents beyond the new end, and it can leave tree_lock unbalanced. Exploitation requires write access to an already-mounted writable HFS+ filesystem and a file with at least 10 extents; the result is lost data and possible filesystem interruption.

CVSS severity7.1
High
EPSS probability0.24%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Data corruption in the Linux kernel HFS+ driver allows local users to lose file data by shrinking a fragmented file on a writable HFS+ volume. hfsplus_file_truncate() unconditionally removes the final overflow extent record instead of freeing only extents beyond the new end, and it can leave tree_lock unbalanced. Exploitation requires write access to an already-mounted writable HFS+ filesystem and a file with at least 10 extents; the result is lost data and possible filesystem interruption.

The record

CVE
CVE-2021-46989
Published
Feb 28, 2024
Updated
Aug 5, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
T1485
Attack vector
local
Privileges
authenticated

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

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Is a vulnerable build present?

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  1. Affected versionversion=31651c607151f1034cfb57e5a78678bea54c362b <52dde855663e5db824af51db39b5757d2ef3e28a
  2. Affected versionversion=31651c607151f1034cfb57e5a78678bea54c362b <97314e45aa1223a42d60256a62c5d9af54baf446
  3. Affected versionversion=31651c607151f1034cfb57e5a78678bea54c362b <adbd8a2a8cc05d9e501f93e5c95c59307874cc99
  4. Affected versionversion=31651c607151f1034cfb57e5a78678bea54c362b <c3187cf32216313fb316084efac4dab3a8459b1d
  5. Affected versionversion=31651c607151f1034cfb57e5a78678bea54c362b <c451a6bafb5f422197d31536f82116aed132b72c
  6. Affected versionversion=31651c607151f1034cfb57e5a78678bea54c362b <c477f62db1a0c0ecaa60a29713006ceeeb04b685
  7. Affected versionversion=4.19

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=31651c607151f1034cfb57e5a78678bea54c362b <52dde855663e5db824af51db39b5757d2ef3e28a; version=31651c607151f1034cfb57e5a78678bea54c362b <97314e45aa1223a42d60256a62c5d9af54baf446; version=31651c607151f1034cfb57e5a78678bea54c362b <adbd8a2a8cc05d9e501f93e5c95c59307874cc99; version=31651c607151f1034cfb57e5a78678bea54c362b <c3187cf32216313fb316084efac4dab3a8459b1d; version=31651c607151f1034cfb57e5a78678bea54c362b <c451a6bafb5f422197d31536f82116aed132b72c; version=31651c607151f1034cfb57e5a78678bea54c362b <c477f62db1a0c0ecaa60a29713006ceeeb04b685; version=4.19

Published CVSS scores

7.1LinuxCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:H
5.5CISACVSS: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

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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

T1485Data Destruction

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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