CVE-2026-49429

Kernel heap overflow in ZFS_IOC_USERSPACE_MANY ioctl

State: Published
Severity: 7.8 High
Published: Aug 19, 2026
Updated: Aug 20, 2026
Reserved: May 29, 2026

Description

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.

Scores

CVSS	Score	Vector	Source
3.1	7.8 High	CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H	CISA-ADP

Weaknesses

CWE-122 Heap-based Buffer Overflow

Affected Products

Product	Versions
FreeBSDFreeBSD	15.1-RELEASE to before p1Affected 15.0-RELEASE to before p11Affected 14.4-RELEASE to before p7Affected 14.3-RELEASE to before p16Affected

References

https://security.freebsd.org/advisories/FreeBSD-SA-26:40.zfs.ascvendor-advisory

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