More Information on SWAPGS and Speculative Only Segment Loads

ID 767611
Updated 8/6/2019
Version Latest



On August 6, 2019, researchers at BitDefender* published details on two issues they reported to both Intel and Microsoft* as part of coordinated vulnerability disclosure (CVD).


Researchers from BitDefender published a paper entitled Bypassing KPTI Using the Speculative Behavior of the SWAPGS Instruction. This information disclosure vulnerability can be used to speculatively access memory, potentially allowing a malicious actor to read privileged data across trust boundaries.

After assessing this issue with industry partners, we determined that the best mitigation would be at the software layer. Microsoft agreed to coordinate remediation efforts, working with the researchers and other industry partners. Microsoft released their software update to address this issue in July 2019 and today published their security advisory as part of the CVD process. 

Some Linux* OS vendors may elect to release updates for their products. Please check with your Linux OS vendor for details.

Speculative only Segment Loads

Researchers from BitDefender also published a paper entitled Security Implications Of Speculatively Executing Segmentation Related Instructions On Intel CPUs. Intel expects, as stated in the paper, that the exploits described by the researchers are addressed through the use of existing mitigation techniques.

We believe strongly in the value of coordinated disclosure and value our partnership with the research community. As a best practice, we continue to encourage everyone to keep their systems up-to-date.


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