Vulnerability Details CVE-2026-49429
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.
Exploit prediction scoring system (EPSS) score
EPSS Score 0.002
EPSS Ranking 6.0%
CVSS Severity
CVSS v3 Score 7.8