What is CVE-2021-29631?

CVE-2021-29631 is a high-severity vulnerability in FreeBSD, classified under Use of Uninitialized Resource. CVSS score: 7.8/10. Published 2021-08-30.

How severe is CVE-2021-29631?

High severity. CVSS v3 base score is 7.8 out of 10.

Vulnerability in FreeBSD

CVE-2021-29631

In FreeBSD 13.0-STABLE before n246941-20f96f215562, 12.2-STABLE before r370400, 11.4-STABLE before r370399, 13.0-RELEASE before p4, 12.2-RELEASE before p10, and 11.4-RELEASE before p13, certain VirtIO-based device models in bhyve failed to handle errors when fetching I/O descriptors. A malicious guest may cause the device model to operate on uninitialized I/O vectors leading to memory corruption, crashing of the bhyve process, and possibly arbitrary code execution in the bhyve process.

Published 2021-08-30 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 7.8 (High). Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H.

EPSS exploit prediction

EPSS: 0.003 (18.9th percentile), scored 2026-09-29.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 19th percentile — 18.9% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.003 · newest: 0.003 · change: 0.000

Affected products

FreeBSD — versions 11.4, 12.2, 13.0
FreeBSD — versions FreeBSD 13.0-RELEASE before p4, 12.2-RELEASE before p10, 11.4-RELEASE before p13

Weakness classification (CWE)

CWE-908 — Use of Uninitialized Resource

References

security.FreeBSD.org/advisories/FreeBSD-SA-21:13.bhyve.asc (Vendor Advisory)
security.netapp.com/advisory/ntap-20210923-0004/ (Third Party Advisory)

Frequently asked questions

What is CVE-2021-29631?: CVE-2021-29631 is a high-severity vulnerability in FreeBSD, classified under Use of Uninitialized Resource. CVSS score: 7.8/10. Published 2021-08-30.
How severe is CVE-2021-29631?: High severity. CVSS v3 base score is 7.8 out of 10.