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.
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.
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Affected Vendors & Products
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Fixes
Solution
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Workaround
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References
History
Wed, 19 Aug 2026 05:30:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| 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. | |
| Title | Kernel heap overflow in ZFS_IOC_USERSPACE_MANY ioctl | |
| Weaknesses | CWE-122 | |
| References |
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MITRE
Status: PUBLISHED
Assigner: freebsd
Published:
Updated: 2026-08-19T05:15:21.198Z
Reserved: 2026-05-29T20:24:28.616Z
Link: CVE-2026-49429
Vulnrichment
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NVD
Status : Received
Published: 2026-08-19T06:17:42.513
Modified: 2026-08-19T06:17:42.513
Link: CVE-2026-49429
Redhat
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OpenCVE Enrichment
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Weaknesses