CVE-2023-23583

Local privilege escalation via redundant REX prefix

Published Nov 14, 2023 · Updated Dec 16, 2025

Unexpected processor behavior in affected Intel processors allows local users to gain kernel privilege, disclose data, or crash or hang systems. Executing REP MOVSB with a redundant REX prefix under specific microarchitectural conditions triggers unpredictable CPU behavior instead of normal instruction handling. Exploitation requires arbitrary local code execution; limited scenarios escalate from CPL3 to CPL0, while other outcomes interrupt service through a crash or hang.

CVSS severity8.8
High
EPSS probability1.73%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Unexpected processor behavior in affected Intel processors allows local users to gain kernel privilege, disclose data, or crash or hang systems. Executing REP MOVSB with a redundant REX prefix under specific microarchitectural conditions triggers unpredictable CPU behavior instead of normal instruction handling. Exploitation requires arbitrary local code execution; limited scenarios escalate from CPL3 to CPL0, while other outcomes interrupt service through a crash or hang.

The record

CVE
CVE-2023-23583
Published
Nov 14, 2023
Updated
Dec 16, 2025
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-1281, T1068, T1499.004
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Nov 14, 2023CVE publishedPublication date reported by the CVE source.
  2. Dec 16, 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

8.8Intel CorporationCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
7.8NISTCVSS: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.

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

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
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-1281Sequence of Processor Instructions Leads to Unexpected Behavior
T1068Exploitation for Privilege Escalation
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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