What is CVE-2021-31571?

CVE-2021-31571 is a critical-severity vulnerability in Amazon Freertos, classified under Integer Overflow or Wraparound. CVSS score: 9.8/10. Published 2021-04-22.

How severe is CVE-2021-31571?

Critical severity. CVSS v3 base score is 9.8 out of 10.

Integer overflow in Amazon Freertos

CVE-2021-31571

The kernel in Amazon Web Services FreeRTOS before 10.4.3 has an integer overflow in queue.c for queue creation.

Vulnerability class: Integer Overflow

Published 2021-04-22 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 9.8 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.

EPSS exploit prediction

EPSS: 0.014 (71.1th percentile), scored 2026-09-29.

Low probability of exploitation in the next 30 days, but still tracked. 71st percentile — 71.1% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.014 · newest: 0.014 · change: 0.000

Affected products

Amazon Freertos

Weakness classification (CWE)

CWE-190 — Integer Overflow or Wraparound

References

github.com/FreeRTOS/FreeRTOS-Kernel/commit/47338393f1f79558f6144213409f09f81d7c… (Patch, Third Party Advisory)

Frequently asked questions

What is CVE-2021-31571?: CVE-2021-31571 is a critical-severity vulnerability in Amazon Freertos, classified under Integer Overflow or Wraparound. CVSS score: 9.8/10. Published 2021-04-22.
How severe is CVE-2021-31571?: Critical severity. CVSS v3 base score is 9.8 out of 10.