CVE-2021-42114: Modern DRAM devices (PC-DDR4, LPDDR4X) are affected by a vulnerability in their internal Target Row Refresh (TRR) mitigation against Rowhammer attacks...

Description

Modern DRAM devices (PC-DDR4, LPDDR4X) are affected by a vulnerability in their internal Target Row Refresh (TRR) mitigation against Rowhammer attacks. Novel non-uniform Rowhammer access patterns, consisting of aggressors with different frequencies, phases, and amplitudes allow triggering bit flips on affected memory modules using our Blacksmith fuzzer. The patterns generated by Blacksmith were able to trigger bitflips on all 40 PC-DDR4 DRAM devices in our test pool, which cover the three major DRAM manufacturers: Samsung, SK Hynix, and Micron. This means that, even when chips advertised as Rowhammer-free are used, attackers may still be able to exploit Rowhammer. For example, this enables privilege-escalation attacks against the kernel or binaries such as the sudo binary, and also triggering bit flips in RSA-2048 keys (e.g., SSH keys) to gain cross-tenant virtual-machine access. We can confirm that DRAM devices acquired in July 2020 with DRAM chips from all three major DRAM vendors (Samsung, SK Hynix, Micron) are affected by this vulnerability. For more details, please refer to our publication.

Metrics

CVSS 3.1

8.3/10

CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H

EPSS Probability

2.89%

85.1th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-20

Affected Software

Vendor	Product	Versions
Samsung	Ddr4 Sdram Firmware	All versions
Samsung	Lddr4 Firmware	All versions
Micron	Lddr4 Firmware	All versions
Micron	Ddr4 Sdram Firmware	All versions
Skhynix	Ddr4 Sdram Firmware	All versions
Skhynix	Lddr4 Firmware	All versions

References

https://comsec.ethz.ch/research/dram/blacksmith/Exploit, Third Party Advisory
https://comsec.ethz.ch/wp-content/files/blacksmith_sp22.pdfExploit, Third Party Advisory
https://github.com/comsec-group/blacksmithExploit, Third Party Advisory
https://comsec.ethz.ch/research/dram/blacksmith/Exploit, Third Party Advisory
https://comsec.ethz.ch/wp-content/files/blacksmith_sp22.pdfExploit, Third Party Advisory
https://github.com/comsec-group/blacksmithExploit, Third Party Advisory

Timeline

Published: Nov 16, 2021
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2021-42114?

Modern DRAM devices (PC-DDR4, LPDDR4X) are affected by a vulnerability in their internal Target Row Refresh (TRR) mitigation against Rowhammer attacks. Novel non-uniform Rowhammer access patterns, consisting of aggressors with different frequencies, phases, and amplitudes allow triggering bit flips on affected memory modules using our Blacksmith fuzzer. The patterns generated by Blacksmith were able to trigger bitflips on all 40 PC-DDR4 DRAM devices in our test pool, which cover the three major DRAM manufacturers: Samsung, SK Hynix, and Micron. This means that, even when chips advertised as Rowhammer-free are used, attackers may still be able to exploit Rowhammer. For example, this enables privilege-escalation attacks against the kernel or binaries such as the sudo binary, and also triggering bit flips in RSA-2048 keys (e.g., SSH keys) to gain cross-tenant virtual-machine access. We can confirm that DRAM devices acquired in July 2020 with DRAM chips from all three major DRAM vendors (Samsung, SK Hynix, Micron) are affected by this vulnerability. For more details, please refer to our publication.

How severe is CVE-2021-42114?

CVE-2021-42114 has a CVSS score of 8.3/10 (HIGH severity). The EPSS model estimates a 2.89% probability of exploitation in the next 30 days.

How do I fix CVE-2021-42114?

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.