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CVE-2026-49429— Kernel heap overflow in ZFS_IOC_USERSPACE_MANY ioctl

Quick assessment

Affected
FreeBSD FreeBSD
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

zfs-userspace(8) 所使用的 ioctl 在处理内核内存分配时，将 64 位的输出缓冲区大小截断为 32 位整数，但在写入记录时却使用了原始的 64 位大小作为缓冲区边界限制。 具有 “userused” 委托 ZFS 权限的本地用户可通过触发 ioctl 引发内核堆溢出，从而可能导致权限提升。

AI Predicted 7.8 Difficulty: Moderate EPSS 0.17% · P6

Affected Version Matrix 4

VendorProduct Version RangeStatus
FreeBSD FreeBSD 15.1-RELEASE< p1 affected
15.0-RELEASE< p11 affected
14.4-RELEASE< p7 affected
14.3-RELEASE< p16 affected
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I. Basic Information for CVE-2026-49429

Vulnerability Information
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Vulnerability Title
Kernel heap overflow in ZFS_IOC_USERSPACE_MANY ioctl
Source: CVE Program / CVE List V5
Vulnerability 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.
Source: CVE Program / CVE List V5
CVSS Information
N/A
Source: CVE Program / CVE List V5
Vulnerability Type
堆缓冲区溢出
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
FreeBSD FreeBSD 15.1-RELEASE ~ p1 -

II. Public POCs for CVE-2026-49429

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III. Intelligence Information for CVE-2026-49429

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Vendor Advisories for CVE-2026-49429 (1)

Same Patch Batch · FreeBSD · 2026-08-19 · 23 CVEs total

CVE-2026-49423 Remote DOS via uninitialized memory access in KTLS receive
CVE-2026-58087 Heap out-of-bounds access in semctl(2)
CVE-2026-58088 Race condition in ELF core dump segment counting
CVE-2026-58083 Use-after-free in kqueue copy-on-fork
CVE-2026-58084 Kernel stack disclosure via timer_settime(2)
CVE-2026-58085 Missing MAC validation in wg(4) packet decryption
CVE-2026-58086 ktrace(2) privilege incorrectly validated in jails
CVE-2026-49425 Kernel stack disclosure in 32-bit compatibility support
CVE-2026-49424 Kernel stack disclosure in Linux compatibility layer
CVE-2026-58081 Heap based buffer overflow in iconv(3)
CVE-2026-58082 Stack based buffer overflow in iconv(3)
CVE-2026-49418 Use-after-free in device pager page list
CVE-2026-49426 Incorrect audit records for ptrace(2) syscall requests
CVE-2026-49427 posixshm: largepage shared memory objects not explicitly wired
CVE-2026-49428 posixshm: system calls can incorrectly free memory of largepage objects
CVE-2026-49420 Buffer overflow in libalias RTSP handler
CVE-2026-49422 Use-after-free in TCP RACK stack option handler
CVE-2026-49421 unlinkat(2) ignores AT_RESOLVE_BENEATH flag
CVE-2026-49430 Kernel heap overflow in ZFS_IOC_RECV_NEW ioctl
CVE-2026-49431 Incorrect user validation in ZFS_IOC_SET_PROP ioctl

Showing top 20 of 23 CVEs. View all on vendor page &rarr; →

IV. Related Vulnerabilities

Same product: FreeBSD
Same vendor: FreeBSD
Same weakness: CWE-122

V. Comments for CVE-2026-49429

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