Guest compromise via skipped TLB flushes
Published Dec 10, 2021 · Updated Sep 16, 2024
TLB isolation failure in AMD EPYC Server CPUs through 3rd Gen allows attackers to alter or read data in SEV/SEV-ES guests. The hypervisor-controlled VMCB TLB control field can omit a required flush, causing a victim process to reuse address translations injected by another guest process. Exploitation requires a malicious hypervisor and suitable guest execution, and it can redirect privileged execution, expose guest data, or bypass authentication.
Summary
What happened
TLB isolation failure in AMD EPYC Server CPUs through 3rd Gen allows attackers to alter or read data in SEV/SEV-ES guests. The hypervisor-controlled VMCB TLB control field can omit a required flush, causing a victim process to reuse address translations injected by another guest process. Exploitation requires a malicious hypervisor and suitable guest execution, and it can redirect privileged execution, expose guest data, or bypass authentication.
The record
- CVE
- CVE-2021-26340
- Published
- Dec 10, 2021
- Updated
- Sep 16, 2024
- Vendor
- AMD
- Product
- AMD EPYC Server CPUs
- Classifications
- T1565
- Attack vector
- local
- Privileges
- admin
Timeline
How it unfolded
- Dec 10, 2021CVE publishedPublication date reported by the CVE source.
- Sep 16, 2024Record 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.
- Affected versionversion=Processor <=3rd gen EPYC
What conditions does exploitation require?
What is affected?
Published CVSS scores
No CVSS assessment is available in this record.
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.
Weakness, pattern, technique
Public exploit references
- TLB Poisoning Attacks on AMD Secure Encrypted Virtualizationfunctional · demonstrated
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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