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CVE-2026-72192
ntfs3: bound to_move in indx_insert_into_root before hdr_insert_head
Published 2026-08-15 (2 months ago) by the Linux kernel CNA. Subsystem fs/ntfs3. Debian urgency: not yet assigned.
What to do, per Debian release
Debian's own status for CVE-2026-72192 in every release this site tracks, and what each one means in practice. Every status below is the one the Debian Security Team publishes for this CVE. source
| Release | Status | Version | What this means |
|---|---|---|---|
| Debian 12bookworm | fixed | 6.1.180-1 | Update the kernel and reboot. Fixed in 6.1.180-1. A running kernel keeps the old code until the machine restarts. |
| Debian 13trixie | fixed | 6.12.100-1 | Update the kernel and reboot. Fixed in 6.12.100-1. A running kernel keeps the old code until the machine restarts. |
| Debian 14forky | fixed | 7.1.5-1 | Update the kernel and reboot. Fixed in 7.1.5-1. A running kernel keeps the old code until the machine restarts. |
| Debian unstablesid | fixed | 7.1.5-1 | Update the kernel and reboot. Fixed in 7.1.5-1. A running kernel keeps the old code until the machine restarts. |
The vulnerability
What the bug is
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.
Where it lives
The fix touches these files. If the subsystem is one you do not use, the practical exposure is lower, though the package is still the vulnerable one.
fs/ntfs3/index.c
- What this is
- NTFS3 FILESYSTEMMAINTAINERS section matched on fs/ntfs3/ · ntfs3@lists.linux.dev · Supported
- Kernel module
- ntfs3
Check it on the machine
grep -w CONFIG_NTFS3_FS /boot/config-$(uname -r)Reads the booted kernel's own configuration, on the machine and nowhere else. =y is built in, =m is a module, and an is not set line means the code is not there.
lsmod | grep -w ntfs3Prints a line if that module is loaded right now, and nothing if it is not. One that is not loaded can still be loaded later by anything that needs it.
Show whether Debian builds this, per release
Debian does not build this code in 3 releases. It does build it in 1 release, so the answer depends on which release the machine runs.
- bookwormn
- trixiem
- forky, sidn
- n
- not enabled on any flavour - this release does not build the code
- m
- a loadable module on every flavour - check lsmod, can be blacklisted
- Build switch
- CONFIG_NTFS3_FS
From the configuration Debian publishes for every kernel flavour it builds. It covers only the architectures Debian ships a linux-config package for, and nothing about a kernel you built yourself. Debian's own status above stays authoritative about the source package.MAINTAINERS kbuild Makefiles Debian linux-config packages
Signals
- Published
- 2026-08-15 (2 months ago)source
- CVSS
- 9.8 critical
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:Hsource recompute it - Attack vector
- network (AV:N)source
- EPSS
- 0.74%, higher than 53.6% of all CVEssource
- CISA KEV
- not listedthe KEV catalogue
- Debian urgency
- not yet assignedsource
- Subsystem
- fs/ntfs3
Upstream fixes
The versions the CNA records as introducing and fixing this, and the commit for each. source
| Introduced | Fixed in | Commit |
|---|---|---|
| 5.15 | 5.15.212 | 0af83b8155cc |
| 5.15 | 6.1.178 | cb3161deebca |
| 5.15 | 6.6.145 | 53c5f3b2da37 |
| 5.15 | 6.12.97 | 194b00c99ba9 |
| 5.15 | 6.18.40 | aaa1f956c0fc |
| 5.15 | 7.1.5 | d240f5f9d036 |
| 5.15 | 7.2 | 9b6926ac9c97 |
Why the CNA scored it this way
Quoted from the kernel CNA's own scoring file, word for word. A highlighted metric carries the most severe value CVSS v3.1 defines for it, which is what pushes the score up. source
- AV:NAttack vector, network
- 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:LAttack complexity, low
- 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:NPrivileges required, none
- 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:NUser interaction, none
- 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:UScope, unchanged
- 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:HConfidentiality impact, high
- 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:HIntegrity impact, high
- 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:HAvailability impact, high
- 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.