CVE-2023-3494: Freebsd

High severity, CVSS 8.8. EPSS: 0.2% chance of exploitation in the next 30 days.

The fwctl driver implements a state machine which is executed when a bhyve guest accesses certain x86 I/O ports. The interface lets the guest copy a string into a buffer resident in the bhyve process' memory. A bug in the state machine implementation can result in a buffer overflowing when copying this string. Malicious, privileged software running in a guest VM can exploit the buffer overflow to achieve code execution on the host in the bhyve userspace process, which typically runs as root, mitigated by the capabilities assigned through the Capsicum sandbox available to the bhyve process.

Affected products

• Freebsd Freebsd: version 13.1 only; version 13.2 only

Published 2023-08-01. Last modified 2026-06-17.