CVE-2021-3966: zephyrproject-rtos zephyr Heap-based Buffer Overflow
CVSS: 9.6v3.1CriticalModified
Published 11-01-2023Last modified 09-04-2025
Vulnerability summary
CVE-2021-3966 is a critical (CVSS 9.6) Heap-based Buffer Overflow vulnerability in zephyrproject-rtos zephyr. EPSS estimates a 0.49% chance of exploitation in the next 30 days, higher than 40.6% of scored vulnerabilities.
CVSS score
9.6/10
010
Critical · v3.1 (CVE.org)EPSS score
0.49%
0%100%
Low · 0.00 pp in 30 daysKEVNot listedIn no KEV catalog
RansomwareNone recordedNo known use recorded
Public exploits0No public exploits recorded
Timeline
- 11-01-2023PublishedVulnerability first disclosed.
- 09-04-2025Last modifiedVulnerability information updated.
Description
usb device bluetooth class includes a buffer overflow related to implementation of net_buf_add_mem.
CVSS metrics
2 scores · 2 sources · 1 versionCritical 9.6Preferred score · CVE.org (CNA)
CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:L/I:H/A:HSources2 sources · 8.8–9.6
- NVDNIST8.8HighCVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:HDiffers
EPSS trend
Probability
0.49%
Chance of exploitation in the next 30 days
Percentile
41%
Versus all other CVEs
30-day change
0.00 pp
From 0.49% on 20-09-2026
20-09-202620-10-2026
EPSS score0.49%
Known exploited
Compare KEV catalogsNot in any of the 3 tracked catalogs.
Public exploits
0 foundNo public exploits indexed.
Weaknesses
CWE · root cause- CWE-122Heap-based Buffer OverflowA heap overflow condition is a buffer overflow, where the buffer that can be overwritten is allocated in the heap portion of memory, generally meaning that the buffer was allocated using a routine such as malloc().
- CWE-120Buffer Copy without Checking Size of Input ('Classic Buffer Overflow')The product copies an input buffer to an output buffer without verifying that the size of the input buffer is less than the size of the output buffer.
Affected systems
2 vendors · 2 products
References
1 links- github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-hfxq-3w6x-fv2mThird Party Advisory