What is CVE-2021-3321?

CVE-2021-3321 is a high-severity vulnerability in Zephyrproject Zephyr, classified under Integer Overflow to Buffer Overflow. CVSS score: 7.5/10. Published 2021-10-12.

How severe is CVE-2021-3321?

High severity. CVSS v3 base score is 7.5 out of 10.

Integer overflow in Zephyrproject Zephyr

CVE-2021-3321

Integer Underflow in Zephyr in IEEE 802154 Fragment Reassembly Header Removal. Zephyr versions >= >=2.4.0 contain Integer Overflow to Buffer Overflow (CWE-680). For more information, see https://github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-w44j-66g7-xw99

Published 2021-10-12 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:C/C:L/I:L/A:H.

EPSS exploit prediction

EPSS: 0.008 (53.5th percentile), scored 2026-09-29.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 54th percentile — 53.5% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.008 · newest: 0.008 · change: 0.000

Affected products

Zephyrproject Zephyr
Zephyrproject-Rtos Zephyr — versions >=2.4.0

Weakness classification (CWE)

References

github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-w44j-66g7-xw99 (Exploit, Patch, Third Party Advisory)

Frequently asked questions

What is CVE-2021-3321?: CVE-2021-3321 is a high-severity vulnerability in Zephyrproject Zephyr, classified under Integer Overflow to Buffer Overflow. CVSS score: 7.5/10. Published 2021-10-12.
How severe is CVE-2021-3321?: High severity. CVSS v3 base score is 7.5 out of 10.