Live › vulnerability › CVE-2026-98985
Go to dashboardIn the Linux kernel's pivot_root() and chroot() path, the kernel reads the parent of a mount that may already be freed after its last reference was dropped via a file descriptor. The sources describe a KASAN use-after-free read; the reported impact is a crash or memory corruption in kernel context, and the sources do not state a confirmed privilege escalation.
Summary written from the sources below. Check the originals before acting.
First seen by InfraStack 2026-10-23 21:57 UTC. All times on this page are UTC.
Systems running a Linux kernel without the upstream fix for pivot_root() and chroot() mount parent checks. The sources do not say which kernel versions are affected or which configurations, so the exact scope is unknown.
No product ranges from the sources yet.
Each row is the first time that source carried this signal. The analyst’s rows are its own findings.
In the Linux kernel, the following vulnerability has been resolved:
namespace: check the mounts before reading their parents in pivot_root()
path_pivot_root() reads the parents of new_root and of the caller's root and checks whether they are shared before it checks that either mount is in the caller's mount namespace. Only namespace_sem is held. That's fine for a mount that is in the caller's mount namespace.
But new_root can be a file descriptor to a mount that has been unmounted and that only the file descriptor keeps alive. If that mount stayed attached to its parent when it was unmounted nothing pins the parent for it. The final mntput() of the parent unhooks the children under mount_lock alone and frees the parent afterwards:
pivot_root() close(fd), last ref on the parent
ex_parent = new_mnt->mnt_parent mntput_no_expire_slowpath() __umount_mnt(new_mnt) cleanup_mnt() call_rcu() IS_MNT_SHARED(ex_parent)
BUG: KASAN: slab-use-after-free in path_pivot_root+0xf1a/0x1840 Read of size 4 at addr ffff8881047382f8 by task pivot_widen/157 path_pivot_root+0xf1a/0x1840 __x64_sys_pivot_root+0x165/0x190
The same goes for the caller's root via chroot(). Both outcomes of the check end in EINVAL so nothing but the read itself goes wrong. It's the same thing commit bb4609405752 ("statmount: read the parent of an unmounted mount under mount_lock") fixed for statmount().
Check that both mounts are in the caller's namespace before their parents are read. Every path returns EINVAL either way.
This page as .md · .json · in your agent: get_signal("CVE-2026-98985")
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