CVE-2021-3320

Type Confusion in 802154 ACK Frames Handling

5.9 Medium

Type Confusion in 802154 ACK Frames Handling. Zephyr versions >= v2.4.0 contain NULL Pointer Dereference (CWE-476). For more information, see https://github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-27r3-rxch-2hm7

Attack profile

How easy it is to exploit

Attack vector: Network
Complexity: High
Privileges needed: None
User interaction: None

What an attacker can affect

Confidentiality: None
Integrity: None
Availability: High

Exploit likelihood

0.85%Up 0.4 points since May 25, 2021

What each source reports

CVE List Score used 5.9

Type Confusion in 802154 ACK Frames Handling

Record: CVE-2021-3320
CVSS 3.1: 5.9 MediumCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
Weakness: CWE-476
Updated: 2026-11-02

EUVDEUVD-2021-26651 5.9

Record: EUVD-2021-26651
CVSS 3.1: 5.9 MediumCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
Updated: 2026-11-03

NVD 5.9

Record: CVE-2021-3320
CVSS 3.1: 5.9 MediumCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
CVSS 3.1: 7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
CVSS 2.0: 5.0 MediumAV:N/AC:L/Au:N/C:N/I:N/A:P
Weakness: CWE-476, CWE-843
Updated: 2026-11-02

Affected products

History

History
Recorded	Changed	Sources
Nov 3, 2026	aliases, published	EUVD
Nov 2, 2026	first indexed	CVE List, NVD

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2021-3320 is a medium vulnerability (CVSS 5.9) in Zephyrproject Zephyr, published May 24, 2021. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.85%, the 58th percentile. No source names a fixed version.

References

github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-27r3-rxch-2hm7