High severity · published Aug 19, 2026
CVE-2026-49429
Kernel heap overflow in ZFS_IOC_USERSPACE_MANY ioctl
7.8
CVSS
0.2%
EPSS
No
On KEV
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.
CVSS vector
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Attack vector
Local
Complexity
Low
Privileges
Low
User interaction
None
Confidentiality
High
Integrity
High
Availability
High
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.2% · higher than 4% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
FR
FreeBSD · FreeBSD
15.1-RELEASE before p1; 15.0-RELEASE before p11; 14.4-RELEASE before p7; 14.3-RELEASE before p16 · source: vendor, NVD
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-49429
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-49429
Vendor Advisory
https://security.freebsd.org/advisories/FreeBSD-SA-26:40.zfs.asc
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