What is CVE-2020-27211?

CVE-2020-27211 is a medium-severity vulnerability in Nordicsemi Nrf52840, classified under Observable Discrepancy. CVSS score: 5.7/10. Published 2021-05-21.

How severe is CVE-2020-27211?

Medium severity. CVSS v3 base score is 5.7 out of 10.

Vulnerability in Nordicsemi Nrf52840

CVE-2020-27211

Nordic Semiconductor nRF52840 devices through 2020-10-19 have improper protection against physical side channels. The flash read-out protection (APPROTECT) can be bypassed by injecting a fault during the boot phase.

Published 2021-05-21 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 5.7 (Medium). Vector: CVSS:3.1/AV:P/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N.

EPSS exploit prediction

EPSS: 0.003 (17.8th percentile), scored 2026-10-01.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 18th percentile — 17.8% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.003 · newest: 0.003 · change: 0.000

Affected products

Weakness classification (CWE)

CWE-203 — Observable Discrepancy

References

www.aisec.fraunhofer.de/en/FirmwareProtection.html (Third Party Advisory)
eprint.iacr.org/2021/640 (Third Party Advisory)
limitedresults.com/2020/06/nrf52-debug-resurrection-approtect-bypass/ (Third Party Advisory)
infocenter.nordicsemi.com/pdf/in_133_v1.0.pdf (Third Party Advisory)
www.aisec.fraunhofer.de/de/das-institut/wissenschaftliche-exzellenz/security-an… (Third Party Advisory)

Frequently asked questions

What is CVE-2020-27211?: CVE-2020-27211 is a medium-severity vulnerability in Nordicsemi Nrf52840, classified under Observable Discrepancy. CVSS score: 5.7/10. Published 2021-05-21.
How severe is CVE-2020-27211?: Medium severity. CVSS v3 base score is 5.7 out of 10.