CVE-2021-3323: Zephyrproject Zephyr

Critical severity, CVSS 9.8. EPSS: 0.9% chance of exploitation in the next 30 days.

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

Affected products

• Zephyrproject Zephyr: from 2.4.0, before 2.5.0 (fixed in 2.5.0)

Published 2021-10-12. Last modified 2026-06-17.