CVE-2018-18056: An issue was discovered in the Texas Instruments (TI) TM4C, MSP432E and MSP432P microcontroller series. The eXecute-Only-Memory (XOM) implementation p...

Description

An issue was discovered in the Texas Instruments (TI) TM4C, MSP432E and MSP432P microcontroller series. The eXecute-Only-Memory (XOM) implementation prevents code read-outs on protected memory by generating bus faults. However, single-stepping and using breakpoints is allowed in XOM-protected flash memory. As a consequence, it is possible to execute single instructions with arbitrary system states (e.g., registers, status flags, and SRAM content) and observe the state changes produced by the unknown instruction. An attacker could exploit this vulnerability by executing protected and unknown instructions with specific system states and observing the state changes. Based on the gathered information, it is possible to reverse-engineer the executed instructions. The processor acts as a kind of "instruction oracle."

Metrics

EPSS Probability

0.40%

32.3th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-200

Affected Software

Vendor	Product	Versions
Ti	Tm4c123 Firmware	All versions
Ti	Tm4c129 Firmware	All versions

References

https://www.usenix.org/conference/woot19/presentation/schinkTechnical Description, Third Party Advisory
https://www.usenix.org/system/files/woot19-paper_schink.pdfTechnical Description, Third Party Advisory
https://www.usenix.org/conference/woot19/presentation/schinkTechnical Description, Third Party Advisory
https://www.usenix.org/system/files/woot19-paper_schink.pdfTechnical Description, Third Party Advisory

Timeline

Published: Aug 20, 2019
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2018-18056?

An issue was discovered in the Texas Instruments (TI) TM4C, MSP432E and MSP432P microcontroller series. The eXecute-Only-Memory (XOM) implementation prevents code read-outs on protected memory by generating bus faults. However, single-stepping and using breakpoints is allowed in XOM-protected flash memory. As a consequence, it is possible to execute single instructions with arbitrary system states (e.g., registers, status flags, and SRAM content) and observe the state changes produced by the unknown instruction. An attacker could exploit this vulnerability by executing protected and unknown instructions with specific system states and observing the state changes. Based on the gathered information, it is possible to reverse-engineer the executed instructions. The processor acts as a kind of "instruction oracle."

How severe is CVE-2018-18056?

Severity scoring for CVE-2018-18056 is pending analysis. The EPSS model estimates a 0.40% probability of exploitation in the next 30 days.

How do I fix CVE-2018-18056?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.