CVE-2026-99063 is a vulnerability in Linux Kernel
Published on October 23, 2026
dm ioctl: don't let data_start run past the buffer
In the Linux kernel, the following vulnerability has been resolved:
dm ioctl: don't let data_start run past the buffer
struct dm_ioctl has seven bytes of trailing padding, so the smallest
buffer userspace is allowed to ask for, offsetof(struct dm_ioctl, data),
is seven bytes shorter than sizeof(struct dm_ioctl).
get_result_buffer() sets data_start to sizeof(struct dm_ioctl) without
looking at how big the buffer actually is. Ask for the minimum and
data_start ends up seven bytes past the end. Callers add it to
data_size, and ctl_ioctl() copies that much back to userspace:
BUG: KASAN: slab-out-of-bounds in _copy_to_user+0xad/0xd0
Read of size 312 at addr ffff8880169e4c00 by task repro-dm/140
ctl_ioctl+0x5e3/0xcb0
dm_ctl_ioctl+0x25/0x40
allocated 305-byte region [ffff8880169e4c00, ffff8880169e4d31)
A DM_LIST_DEVICES with data_size set to 305 is enough to hit it, and the
seven bytes that leak are whatever sat next to the allocation.
Clamp data_start to the buffer size.
Note that this is not a security bug because the out-of-bounds read can
only be triggered by root.
Products Associated with CVE-2026-99063
Want to know whenever a new CVE is published for Linux Kernel? stack.watch will email you.
Affected Versions
Linux:- Version 76c072b48e39e9291fbf02d6c912cf27d65e093d and below 98195e822343a656b92e235847ab3e72b1a3f920 is affected.
- Version 76c072b48e39e9291fbf02d6c912cf27d65e093d and below e5c3f3d8935ecc64c962fb66e6a86dbf79218f61 is affected.
- Version 76c072b48e39e9291fbf02d6c912cf27d65e093d and below 5680b6fb3054677d4ee65d3baba24b649f1b430e is affected.
- Version 76c072b48e39e9291fbf02d6c912cf27d65e093d and below 725b49c689bbb29ef740b0d6b5ea9390baa9a695 is affected.
- Version 76c072b48e39e9291fbf02d6c912cf27d65e093d and below 9b3fcf519d370df94a56f3b272d9eddffffa5be8 is affected.
- Version 2.6.25 is affected.
- Before 2.6.25 is unaffected.
- Version 6.6.160, <= 6.6.* is unaffected.
- Version 6.12.113, <= 6.12.* is unaffected.
- Version 6.18.57, <= 6.18.* is unaffected.
- Version 7.2.11, <= 7.2.* is unaffected.
- Version 7.3, <= * is unaffected.