CVE-2023-4623

Local privilege escalation via dangling HFSC parent

Published Sep 6, 2023 · Updated Feb 27, 2025

Use-after-free in Linux Kernel 2.6.12 and later before 6.6 allows local users to escalate privileges through malformed HFSC classes. init_vf() inserts a parent without a link-sharing curve into the virtual-time tree, but update_vf() skips its removal and leaves a dangling pointer. A local low-privileged account is required; successful exploitation executes elevated code, while failed memory corruption can crash the system.

CVSS severity7.8
High
EPSS probability0.28%
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 Linux Kernel 2.6.12 and later before 6.6 allows local users to escalate privileges through malformed HFSC classes. init_vf() inserts a parent without a link-sharing curve into the virtual-time tree, but update_vf() skips its removal and leaves a dangling pointer. A local low-privileged account is required; successful exploitation executes elevated code, while failed memory corruption can crash the system.

The record

CVE
CVE-2023-4623
Published
Sep 6, 2023
Updated
Feb 27, 2025
Vendor
The Linux Kernel Organization
Product
Linux Kernel
Classifications
CWE-416, CAPEC-233, T1068
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Sep 6, 2023CVE publishedPublication date reported by the CVE source.
  2. Feb 27, 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?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=2.6.12 <6.6

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linux Kernelversion=2.6.12 <6.6

Published CVSS scores

7.8NIST NVDCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/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-416Use After Free
CAPEC-233Privilege Escalation
T1068Exploitation for Privilege Escalation

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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