CVE-2026-49429 — Kernel heap overflow in ZFS_IOC_USERSPACE_MANY ioctl
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 siz…
Published: 2026-08-19 · CVSS: 7.8 · CVSS 3.1
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.
Source: CVE Program · Revision 8b16575c39f1e1810c5e863010da073d2d3285e7