CVE-2021-3323: Integer Underflow in 6LoWPAN IPHC Header Uncompression in Zephyr

Severity: critical (CVSS 9.8 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.9% probability of exploitation in the next 30 days
Public exploit or detection template: yes
Published: 2021-10-12 · updated 2026-06-17
Weakness: CWE-191

Description

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

How to fix

Upgrade to a fixed version: zephyrproject zephyr 2.5.0. Check the vendor advisory for mitigations.

References

http://github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-89j6-qpxf-pfpc
http://github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-89j6-qpxf-pfpc

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