CVE-2021-43395

Kernel panic via tmpfs lock-order deadlock

Published Dec 26, 2022 · Updated Apr 14, 2025

Improper locking in illumos-derived systems and Oracle Solaris 10 and 11 allows local users to trigger a kernel panic. The tmpfs tdirenter path acquires target and source directory locks in the reverse order used by concurrent rmdir operations, creating an inducible deadlock. An unprivileged local account with access to a tmpfs filesystem can interrupt the entire system by racing crafted rename and rmdir calls.

CVSS severity5.5
Medium
EPSS probability0.32%
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 illumos-derived systems and Oracle Solaris 10 and 11 allows local users to trigger a kernel panic. The tmpfs tdirenter path acquires target and source directory locks in the reverse order used by concurrent rmdir operations, creating an inducible deadlock. An unprivileged local account with access to a tmpfs filesystem can interrupt the entire system by racing crafted rename and rmdir calls.

The record

CVE
CVE-2021-43395
Published
Dec 26, 2022
Updated
Apr 14, 2025
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-667, T1499.004
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Dec 26, 2022CVE publishedPublication date reported by the CVE source.
  2. Apr 14, 2025Record 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 privilegesauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

5.5CISA-ADPCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
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.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

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
T1499.004Application or System Exploitation

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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