CVE-2019-11098

Physical code execution via Boot Guard TOCTOU

Published Jul 14, 2021 · Updated Aug 4, 2024

Insufficient input validation in EDK II MdeModulePkg allows unauthenticated attackers with physical access to execute code via modified SPI flash. During Boot Guard measurement, firmware code is verified from temporary memory but later fetched from SPI flash after that memory is disabled, allowing targeted flash transactions to replace the Initial Boot Block. Physical access to the SPI flash is required; the documented consequence is execution of unsigned firmware code with potential privilege escalation, information disclosure, or service disruption.

CVSS severity6.8
Medium
EPSS probability0.34%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Insufficient input validation in EDK II MdeModulePkg allows unauthenticated attackers with physical access to execute code via modified SPI flash. During Boot Guard measurement, firmware code is verified from temporary memory but later fetched from SPI flash after that memory is disabled, allowing targeted flash transactions to replace the Initial Boot Block. Physical access to the SPI flash is required; the documented consequence is execution of unsigned firmware code with potential privilege escalation, information disclosure, or service disruption.

The record

CVE
CVE-2019-11098
Published
Jul 14, 2021
Updated
Aug 4, 2024
Vendor
TianoCore
Product
EDK II
Classifications
CWE-20, T1601.001
Attack vector
physical
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jul 14, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 4, 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?

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  1. Affected versionversion=See references

What conditions does exploitation require?

Attack vectorphysical
Required privilegesunauthenticated

What is affected?

TianoCore · EDK IIversion=See references

Published CVSS scores

4.6NISTAV:L/AC:L/Au:N/C:P/I:P/A:P
6.8NISTCVSS:3.1/AV:P/AC:L/PR:N/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.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorphysical
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-20Improper Input Validation
T1601.001System Firmware

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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