In the Linux kernel, the following vulnerability has been resolved:
ntfs3: bound to_move in indx_insert_into_root before hdr_insert_head
indx_insert_into_root() promotes a full resident $INDEX_ROOT into
$INDEX_ALLOCATION and copies all non-last resident root entries into
a newly allocated INDEX_BUFFER via hdr_insert_head(). The source
byte count 'to_move' is summed from the on-disk resident entry sizes
and is independent of the destination buffer size, which comes from
root->index_block_size (via indx->index_bits).
A crafted NTFS image that keeps a valid, full resident root but
shrinks root->index_block_size down to 512 after the root has been
populated makes hdr_insert_head() memcpy attacker-controlled resident
entry bytes past the end of the kmalloc(1u << indx->index_bits)
allocation returned by indx_new(). For a 512-byte destination and a
resident root whose non-last entries total 560 bytes, the memcpy
overruns by 120 bytes and a following memmove extends the highest
written offset to 136 bytes past the allocation. The overflow bytes
are a direct copy of on-disk entries (via kmemdup), so they are
fully attacker-controlled.
The write is reachable from unprivileged open(O_CREAT) on a mounted
crafted NTFS image: a single sufficiently long create in a directory
whose resident root is already full forces root promotion and
triggers the copy.
This is a controlled out-of-bounds write of 120-136 bytes past a
kmalloc(index_block_size) allocation, with attacker-controlled
content. It is a bounded adjacent-heap corruption primitive; it is
not an arbitrary-address write. Successful exploitation into a named
victim object depends on the surrounding slab layout.
Reject the copy at the sink. The destination's INDEX_HDR already
reports hdr_total (the payload capacity of the new buffer) and
hdr_used (the bytes already consumed by the terminal END entry
installed by indx_new()); require that to_move fits in the remaining
payload before calling hdr_insert_head(). On mismatch, fail with
-EINVAL and mark the filesystem as having a detected on-disk
inconsistency, which is the same behaviour as the surrounding
validation in this function.
CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
CVSS Score: 9.8
AV:N - ntfs3 registers export_operations; on NAS/hybrid servers exporting an NTFS volume via nfsd or ksmbd, a remote client's CREATE reaches vfs_create→ntfs_create→ntfs_create_inode→indx_insert_entry→indx_insert_into_root without any local syscall from the attacker.
AC:L - The attacker fully controls on-disk $INDEX_ROOT layout (resident entry sizes and index_block_size); a single create in a full resident directory deterministically forces root promotion and the unchecked hdr_insert_head() copy, with no races or victim-specific heap layout required to trigger the overflow.
PR:N - Exploitation needs only write access to create a file in the target directory on an NFS/SMB-exported NTFS share (including guest/anonymous write), or supplying removable media later mounted by the host; no init-namespace root or CAP_SYS_ADMIN is required on the trigger path.
UI:N - Once an administrator has mounted and optionally exported the NTFS volume—or desktop/kiosk automount has attached removable media—the attacker issues open(O_CREAT)/touch/mkdir directly; no further victim clicks, file opens, or cooperative actions beyond that standing configuration are required.
S:U - Impact is attacker-controlled kernel heap corruption and panic within the host kernel's security authority; this is standard local or network filesystem exploitation, not a VM escape, IOMMU bypass, or cross-scope sandbox breakout.
C:H - hdr_insert_head() memcpy/memmove writes 120-136 attacker-controlled bytes past the kzalloc(1u<<index_bits) INDEX_BUFFER allocation; adjacent-heap corruption can disclose or influence neighboring slab objects and is scored as arbitrary-read potential under memory-corruption guidance.
I:H - The overflow is a bounded but fully attacker-controlled out-of-bounds write past a kmalloc allocation during directory index promotion; such heap corruption is exploitable for metadata/control-structure overwrite and kernel code execution, not merely a benign crash.
A:H - Corrupting kmalloc-allocated index buffers via unchecked memcpy/memmove can trigger KASAN faults, kernel oops, or panic; sibling ntfs3 index-insertion overflows in the same call chain are confirmed crash/panic primitives, scoring Availability High.
| Attack Vector |
Network |
Scope |
Unchanged |
| Attack Complexity |
Low |
Confidentiality Impact |
High |
| Privileges Required |
None |
Integrity Impact |
High |
| User Interaction |
None |
Availability Impact |
High |
AV:N - ntfs3 registers export_operations; on NAS/hybrid servers exporting an NTFS volume via nfsd or ksmbd, a remote client's CREATE reaches vfs_create→ntfs_create→ntfs_create_inode→indx_insert_entry→indx_insert_into_root without any local syscall from the attacker.
AC:L - The attacker fully controls on-disk $INDEX_ROOT layout (resident entry sizes and index_block_size); a single create in a full resident directory deterministically forces root promotion and the unchecked hdr_insert_head() copy, with no races or victim-specific heap layout required to trigger the overflow.
PR:N - Exploitation needs only write access to create a file in the target directory on an NFS/SMB-exported NTFS share (including guest/anonymous write), or supplying removable media later mounted by the host; no init-namespace root or CAP_SYS_ADMIN is required on the trigger path.
UI:N - Once an administrator has mounted and optionally exported the NTFS volume—or desktop/kiosk automount has attached removable media—the attacker issues open(O_CREAT)/touch/mkdir directly; no further victim clicks, file opens, or cooperative actions beyond that standing configuration are required.
S:U - Impact is attacker-controlled kernel heap corruption and panic within the host kernel's security authority; this is standard local or network filesystem exploitation, not a VM escape, IOMMU bypass, or cross-scope sandbox breakout.
C:H - hdr_insert_head() memcpy/memmove writes 120-136 attacker-controlled bytes past the kzalloc(1u<<index_bits) INDEX_BUFFER allocation; adjacent-heap corruption can disclose or influence neighboring slab objects and is scored as arbitrary-read potential under memory-corruption guidance.
I:H - The overflow is a bounded but fully attacker-controlled out-of-bounds write past a kmalloc allocation during directory index promotion; such heap corruption is exploitable for metadata/control-structure overwrite and kernel code execution, not merely a benign crash.
A:H - Corrupting kmalloc-allocated index buffers via unchecked memcpy/memmove can trigger KASAN faults, kernel oops, or panic; sibling ntfs3 index-insertion overflows in the same call chain are confirmed crash/panic primitives, scoring Availability High.
CVSS 3.1