CVE-2026-49429: Freebsd

High severity, CVSS 7.8. EPSS: 0.2% chance of exploitation in the next 30 days.

The ZFS_IOC_USERSPACE_MANY ioctl, used by zfs-userspace(8), truncated a 64-bit output buffer size to a 32-bit integer for the kernel allocation, but used the original 64-bit size as the buffer limit when writing records. A local user with the "userused" delegated ZFS permission can trigger a kernel heap overflow via the ZFS_IOC_USERSPACE_MANY ioctl, potentially escalating privileges.

Affected products

• Freebsd Freebsd: version 14.3 only; version 14.4 only; version 15.0 only; version 15.1 only

Published 2026-08-19. Last modified 2026-09-01.