The developer builds a security-critical protection mechanism into the software, but the processor optimizes the execution of the program such that the mechanism is removed or modified.

Primary
This weakness does not depend on other weaknesses and is the result of choices made by the processor in executing the specified application.

Architecture and Design
Optimizations built into the design of the processor can have unintended consequences during the execution of an application.

Low

Integrity
Bypass Protection Mechanism
High
A successful exploitation of this weakness will change the order of an application's execution and will likely be used to bypass specific protection mechanisms. This bypass can be exploited further to potentially read data that should otherwise be unaccessible.

White Box
In theory this weakness can be detected through the use of white box testing techniques where specifically crafted test cases are used in conjunction with debuggers to verify the order of statements being executed.
Opportunistic
Although the mentioned detection method is theoretically possible, the use of speculative execution is a preferred way of increasing processor performance. The reality is that a large number of statements are executed out of order, and determining if any of them break an access control property would be extremely opportunistic.

CVE-2017-5715
Intel, ARM, and AMD processor optimizations related to speculative execution and branch prediction cause access control checks to be bypassed when placing data into the cache. Often known as "Spectre".
https://www.cve.org/CVERecord?id=CVE-2017-5715

CVE-2017-5753
Intel, ARM, and AMD processor optimizations related to speculative execution and branch prediction cause access control checks to be bypassed when placing data into the cache. Often known as "Spectre".
https://www.cve.org/CVERecord?id=CVE-2017-5753

CVE-2017-5754
Intel processor optimizations related to speculative execution cause access control checks to be bypassed when placing data into the cache. Often known as "Meltdown".
https://www.cve.org/CVERecord?id=CVE-2017-5754

Allowed
This CWE entry is at the Base level of abstraction, which is a preferred level of abstraction for mapping to the root causes of vulnerabilities.
Carefully read both the name and description to ensure that this mapping is an appropriate fit. Do not try to 'force' a mapping to a lower-level Base/Variant simply to comply with this preferred level of abstraction.

As of CWE 4.9, members of the CWE Hardware SIG are closely analyzing this entry and others to improve CWE's coverage of transient execution weaknesses, which include issues related to Spectre, Meltdown, and other attacks. Additional investigation may include other weaknesses related to microarchitectural state. As a result, this entry might change significantly in CWE 4.10.

CWE Content Team
MITRE
2018-03-07
3.1
2018-03-29

CWE Content Team
MITRE
2020-02-24
updated Relationships

CWE Content Team
MITRE
2020-06-25
updated Relationships

CWE Content Team
MITRE
2021-03-15
updated Related_Attack_Patterns

CWE Content Team
MITRE
2022-10-13
updated Applicable_Platforms, Maintenance_Notes

CWE Content Team
MITRE
2023-04-27
updated Relationships

CWE Content Team
MITRE
2023-06-29
updated Mapping_Notes