PT-2026-61097 · Linux · Linux

CVE-2026-53392 · Published 2026-07-19 · Updated 2026-07-19

NVD

CVSS v3.1

7.5

High

Base vector

AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

In the Linux kernel, the following vulnerability has been resolved:

NFSv4/flexfiles: reject zero filehandle version count

ff layout alloc lseg() decodes the filehandle-version array count from the flexfiles layout body. The value is used as the count for kzalloc objs(), and the current code only rejects NULL.

A zero count yields ZERO SIZE PTR, which can be stored in dss info->fh versions even though later flexfiles paths assume that at least one filehandle version exists.

Reject fh count == 0 before the allocation, matching the existing zero version count validation in the flexfiles GETDEVICEINFO parser.

A QEMU/KASAN run with a malformed flexfiles layout hit:

KASAN: null-ptr-deref in range [0x0000000000000010-0x0000000000000017] RIP: 0010:ff layout encode ff layoutupdate.isra.0+0x15f/0x750 ff layout encode layoutreturn+0x683/0x970 nfs4 xdr enc layoutreturn+0x278/0x3a0 Kernel panic - not syncing: Fatal exception

The patched kernel rejects the malformed layout without KASAN/oops/panic, and a valid fh count=1 regression still opens, reads, and unmounts cleanly.

Fix

Related Identifiers

CVE-2026-53392

Affected Products

Linux

References · 5

• https://nvd.nist.gov/vuln/detail/CVE-2026-53392 · Security Note
• https://git.kernel.org/stable/c/d8c90c7cc061265d5f2813a1f5c82ef2f4707e67 · Note
• https://git.kernel.org/stable/c/2131ed64b767ffa8bcdb3677d90f3964e39aabc8 · Note
• https://git.kernel.org/stable/c/7779c85028a0676fb190cde4f0c540f4f8e97761 · Note
• https://git.kernel.org/stable/c/2c6bb3c40bc24f6aa8dfbe6fe98c3ad6389203f2 · Note