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Date: Tue, 14 Nov 2023 11:24:30 -0800
From: Antonio Gomez Iglesias <>
To: HW42 <>, <>, Solar Designer
CC: Tavis Ormandy <>
Subject: Re: CVE-2023-23583: Intel - Denial of Service -
 Privilege Escalation (Reptar)

On 11/14/23 11:19 AM, HW42 wrote:
> Solar Designer:
>> On Tue, Nov 14, 2023 at 10:31:51AM -0800, Antonio Gomez Iglesias wrote:
>>> Name of the issue: Redundant Prefix Issue
>>> Description of the issue
>>> Under certain microarchitectural conditions, Intel has identified cases
>>> where execution of an instruction (REP MOVSB) encoded with a redundant
>>> REX prefix may result in unpredictable system behavior resulting in a
>>> system crash/hang, or, in some limited scenarios, may allow escalation
>>> of privilege from CPL3 to CPL0.
>>> This Redundant Prefix Issue is assigned CVE-2023-23583 with a CVSS Base
>>> Score of 8.8 High CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H.
>>> Mitigation
>>> Intel is providing a microcode update to mitigate this issue:
>> Thank you, Antonio!
>> Here's a writeup and reproducer tool by Tavis Ormandy:
>> The GitHub release page above links to Intel security advisory:
>> which specifies what CPU generations are affected (from 10th generation
>> Intel Core or 3rd generation Xeon Scalable to current), and links to a
>> table with "an exhaustive list of processors" matched against this issue
>> and previously disclosed issues:
>> It also says "Please refer to the technical paper here for additional
>> information", where "here" is a link supposedly to "the technical
>> paper", but it's a non-existent page currently, so I'm not posting the
>> URL yet (not sure if it'll stay the same when the page is published).
> I think that link should point to 
> This one can be found in the affected processors table.
The SA
should now link to the correct page. Thanks for the feedback!

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