How severe is CVE-2021-29631?

CVE-2021-29631 has a CVSS 3.x base score of 7.8, rated high severity. It is exploitable over local access with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2021-29631 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (20th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-29631?

CVE-2021-29631 primarily affects Freebsd. In total, 29 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2021-29631?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

When was CVE-2021-29631 published?

CVE-2021-29631 was published on 2021-08-30 and last updated on 2026-06-17.

CVE-2021-29631

CVE-2021-29631 is a high-severity vulnerability in Freebsd with a CVSS 3.x base score of 7.8. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-908.

Key facts

Severity: High (CVSS 3.x base score 7.8)
CVSS v2: 7.2
EPSS exploit prediction: 0% (20th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-908
Affected product: Freebsd
Published: 2021-08-30
Last modified: 2026-06-17

Description

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.

Frequently asked questions

What is 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.
How severe is CVE-2021-29631?: CVE-2021-29631 has a CVSS 3.x base score of 7.8, rated high severity. It is exploitable over local access with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2021-29631 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (20th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-29631?: CVE-2021-29631 primarily affects Freebsd. In total, 29 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2021-29631?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
When was CVE-2021-29631 published?: CVE-2021-29631 was published on 2021-08-30 and last updated on 2026-06-17.

References

Affected products (29)

cpe:2.3:o:freebsd:freebsd:11.4:-:*:*:*:*:*:*
cpe:2.3:o:freebsd:freebsd:11.4:p1:*:*:*:*:*:*
cpe:2.3:o:freebsd:freebsd:11.4:p10:*:*:*:*:*:*
cpe:2.3:o:freebsd:freebsd:11.4:p11:*:*:*:*:*:*
cpe:2.3:o:freebsd:freebsd:11.4:p12:*:*:*:*:*:*
cpe:2.3:o:freebsd:freebsd:11.4:p13:*:*:*:*:*:*
cpe:2.3:o:freebsd:freebsd:11.4:p2:*:*:*:*:*:*
cpe:2.3:o:freebsd:freebsd:11.4:p3:*:*:*:*:*:*
cpe:2.3:o:freebsd:freebsd:11.4:p4:*:*:*:*:*:*
cpe:2.3:o:freebsd:freebsd:11.4:p5:*:*:*:*:*:*
cpe:2.3:o:freebsd:freebsd:11.4:p6:*:*:*:*:*:*
cpe:2.3:o:freebsd:freebsd:11.4:p7:*:*:*:*:*:*
cpe:2.3:o:freebsd:freebsd:11.4:p8:*:*:*:*:*:*
cpe:2.3:o:freebsd:freebsd:11.4:p9:*:*:*:*:*:*
cpe:2.3:o:freebsd:freebsd:12.2:-:*:*:*:*:*:*
cpe:2.3:o:freebsd:freebsd:12.2:p1:*:*:*:*:*:*
cpe:2.3:o:freebsd:freebsd:12.2:p10:*:*:*:*:*:*
cpe:2.3:o:freebsd:freebsd:12.2:p2:*:*:*:*:*:*
cpe:2.3:o:freebsd:freebsd:12.2:p3:*:*:*:*:*:*
cpe:2.3:o:freebsd:freebsd:12.2:p4:*:*:*:*:*:*
cpe:2.3:o:freebsd:freebsd:12.2:p5:*:*:*:*:*:*
cpe:2.3:o:freebsd:freebsd:12.2:p6:*:*:*:*:*:*
cpe:2.3:o:freebsd:freebsd:12.2:p7:*:*:*:*:*:*
cpe:2.3:o:freebsd:freebsd:12.2:p8:*:*:*:*:*:*
cpe:2.3:o:freebsd:freebsd:12.2:p9:*:*:*:*:*:*
cpe:2.3:o:freebsd:freebsd:13.0:-:*:*:*:*:*:*
cpe:2.3:o:freebsd:freebsd:13.0:p1:*:*:*:*:*:*
cpe:2.3:o:freebsd:freebsd:13.0:p2:*:*:*:*:*:*
cpe:2.3:o:freebsd:freebsd:13.0:p3:*:*:*:*:*:*

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