CVE-2026-49429 json
Kernel heap overflow in ZFS_IOC_USERSPACE_MANY ioctl
published 2026-08-19 2 mo ago modified 2026-09-01 2 mo ago also EUVD-2026-62239
- cvss
- 7.8
- version 3.1, CNA
- cisa kev
- Not listed
- not in CISA's catalog
- epss
- 0.2%
- EPSS 0.2% chance of exploitation in 30 days, percentile 4%
- public exploits
- 0
- none known
Summary
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.
Patch / fix
- FreeBSD FreeBSD p1, p7, p11, p16
CISA SSVC
- Exploitation
- none
- Automatable
- no
- Technical impact
- total
- Assessed
- 2 mo ago
Exploit prediction
0.15% chance of exploitation in the next 30 days, higher than 4% of all scored CVEs (FIRST EPSS, 2026-11-08).
CVSS scores
| assigned by | version | score | vector |
|---|---|---|---|
| CISA ADP | 3.1 | 7.8 | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H |
| CNA | 3.1 | 7.8 | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H |
Affected products
- FreeBSD FreeBSD
Classification
- Weakness
-
- CWE-122 Heap-based Buffer Overflow
References
-
security.freebsd.org
/advisories/FreeBSD-SA-26:40.zfs.asc
vendor-advisory
Sources
- CVE List CVE-2026-49429
- NVD CVE-2026-49429
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