Buffer overflow in FreeBSD
CVE-2026-49429
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.
Vulnerability class: Buffer Overflow
CVSS v3 metric
CVSS v3 base score 7.8 (High). Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H.
Affected products
Weakness classification (CWE)
References
- secteam@freebsd.org (vendor-advisory)
Frequently asked questions
- What is CVE-2026-49429?
- CVE-2026-49429 is a high-severity vulnerability in FreeBSD, classified under Heap-based Buffer Overflow. CVSS score: 7.8/10. Published 2026-08-19.
- How severe is CVE-2026-49429?
- High severity. CVSS v3 base score is 7.8 out of 10.