What is CVE-2021-3323?

CVE-2021-3323 is a high-severity vulnerability in Zephyrproject Zephyr, classified under Integer Underflow. CVSS score: 8.3/10. Published 2021-10-12.

How severe is CVE-2021-3323?

High severity. CVSS v3 base score is 8.3 out of 10.

Integer overflow in Zephyrproject Zephyr

CVE-2021-3323

Integer Underflow in 6LoWPAN IPHC Header Uncompression in Zephyr. Zephyr versions >= >=2.4.0 contain Integer Underflow (Wrap or Wraparound) (CWE-191). For more information, see https://github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-89j6-qpxf-pfpc

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

CVSS v3 metric

CVSS v3 base score 8.3 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:L.

EPSS exploit prediction

EPSS: 0.009 (59.7th percentile), scored 2026-10-19.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 60th percentile — 59.7% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.009 · newest: 0.009 · change: 0.000

Affected products

Zephyrproject Zephyr
Zephyrproject-Rtos Zephyr — versions >=2.4.0

Weakness classification (CWE)

CWE-191 — Integer Underflow

References

github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-89j6-qpxf-pfpc (Exploit, Patch, Third Party Advisory)

Frequently asked questions

What is CVE-2021-3323?: CVE-2021-3323 is a high-severity vulnerability in Zephyrproject Zephyr, classified under Integer Underflow. CVSS score: 8.3/10. Published 2021-10-12.
How severe is CVE-2021-3323?: High severity. CVSS v3 base score is 8.3 out of 10.