CVE-2026-49429 Kernel heap overflow in ZFS_IOC_USERSPACE_MANY ioctl
A local user with delegated ZFS permissions can trigger a kernel heap overflow via integer truncation, potentially escalating privileges.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-49429?
CVE-2026-49429 is a high-severity vulnerability in Freebsd Freebsd, published on 19 Aug 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official 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.
Weakness: CWE-122
Which versions are affected by CVE-2026-49429?
It affects 1 product.
Products include Freebsd Freebsd.
How do I fix CVE-2026-49429?
No fix has been published for CVE-2026-49429 yet. Limit exposure of the affected software until one is available.
Is CVE-2026-49429 being exploited?
There is no known exploitation of CVE-2026-49429 in the wild and no public exploit code.