EUVD-2026-62239Severity by source
AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Local attack vector and PR:L confirmed by 'userused' delegated permission requirement; AC:L because exploitation is straightforward once that prerequisite exists.
Primary rating from Vendor (freebsd).
CVSS VectorVendor: freebsd
Lifecycle Timeline
3DescriptionCVE.org
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.
AnalysisAI
Kernel heap overflow in FreeBSD's ZFS subsystem via the ZFS_IOC_USERSPACE_MANY ioctl enables local privilege escalation across multiple supported FreeBSD release branches. The flaw stems from an integer width mismatch: the kernel allocates a heap buffer sized by a 32-bit truncation of the caller-supplied 64-bit length, then copies records up to the original 64-bit limit - writing past the end of the allocation. …
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Attack ChainAIDerived
Hypothetical attack flow derived from CVE metadata
Vulnerability AssessmentAI
| Exploitation | Exploitation requires: (1) local interactive or shell access to the FreeBSD system as a non-root user, and (2) the 'userused' ZFS delegated permission explicitly granted to that user on at least one ZFS dataset - this permission is not configured by default and must be set by an administrator using 'zfs allow'. … Additional conditions and limiting factors are described in the full assessment. |
| Risk Assessment | The CVSS 3.1 score of 7.8 (AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H) accurately reflects the risk profile: exploitation is local, requires no user interaction, and - once the prerequisite permission is in place - involves no special complexity. … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in. |
| Exploit Scenario | Full exploit scenario with step-by-step reproduction available after sign-in. |
| Remediation | Apply the vendor-released patches to reach FreeBSD 14.3-RELEASE-p16, FreeBSD 14.4-RELEASE-p7, FreeBSD 15.0-RELEASE-p11, or FreeBSD 15.1-RELEASE-p1 as appropriate for the installed branch; these patch levels are confirmed by FreeBSD Security Advisory FreeBSD-SA-26:40.zfs (https://security.freebsd.org/advisories/FreeBSD-SA-26:40.zfs.asc). … Detailed patch versions, workarounds, and compensating controls in full report. |
Recommended ActionAI
Within 24 hours: inventory all FreeBSD systems using ZFS delegated permissions and map current user access. …
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Same weakness CWE-122 – Heap-based Buffer Overflow
View allSame technique Heap Overflow
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External POC / Exploit Code
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