On Linux, several OpenZFS ioctl authorization checks accept a capability held only within a user-created, unprivileged namespace as equivalent to… (CVE-2026-79619)

CVE-2026-79619 is a Linux OpenZFS vulnerability where ioctl authorization checks accept capabilities from user-created, unprivileged namespaces as if they were real host privileges. This misinterpretation enables local unprivileged users to execute operations normally restricted to root, including creating, importing, and destroying pools, accessing pool event logs, and performing fault injection. Exploitation requires only permission to open /dev/zfs and the ability to create unprivileged user namespaces, with no need for prior access to the ZFS pools or underlying devices.

An unprivileged local user can escalate privileges to perform sensitive ZFS pool administrative tasks and access restricted information. This could lead to unauthorized modification or destruction of storage pools, exposure of event logs, and injection of faults, potentially compromising system stability and data integrity.

Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Until a fix is available, restrict access to /dev/zfs to trusted users only and consider disabling unprivileged user namespace creation if feasible to reduce the attack surface.