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CVE-2026-72204
ntfs: centalize $INDEX_ROOT header validation
Published 2026-08-15 (2 months ago) by the Linux kernel CNA. Subsystem fs/ntfs. Debian urgency: unimportant.
What to do, per Debian release
Debian's own status for CVE-2026-72204 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 | not affected | 6.1.190-1 | Nothing to do. bookworm never shipped the vulnerable code. |
| Debian 13trixie | not affected | 6.12.113-1 | Nothing to do. trixie never shipped the vulnerable code. |
| 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
Add a dedicated helper to perform stricter validation of $INDEX_ROOT and use it for both directory inodes and named index inodes. This keeps the root size and header geometry checks consistent across both read paths.
Where it lives
The fix touches these files. If the subsystem is one you do not use, the practical exposure is lower, though the package is still the vulnerable one.
fs/ntfs/index.c
fs/ntfs/index.h
fs/ntfs/inode.c
- What this is
- NTFS FILESYSTEMMAINTAINERS section matched on fs/ntfs/ · linux-fsdevel@vger.kernel.org · Maintained
- Kernel module
- ntfs
Check it on the machine
grep -w CONFIG_NTFS_FS /boot/config-$(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 ntfsPrints 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 1 release. It does build it in 2 releases, so the answer depends on which release the machine runs. The build rule could not be established for 1 release, so nothing is claimed about those.
- bookwormn
- trixie?
- forky, sidm
- n
- not enabled on any flavour - this release does not build the code
- ?
- not established - no Makefile entry for the affected file
- m
- a loadable module on every flavour - check lsmod, can be blacklisted
Where a release above reads "not established", no build rule for the affected file was found in that release's kernel tree. That is a gap in this lookup, not a finding that the code is absent.
- Build switch
- CONFIG_NTFS_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
- 8.4 high
CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:Hsource recompute it - Attack vector
- local (AV:L)source
- EPSS
- 0.18%, higher than 7.0% of all CVEssource
- CISA KEV
- not listedthe KEV catalogue
- Debian urgency
- unimportantsource
- Subsystem
- fs/ntfs
Upstream fixes
The versions the CNA records as introducing and fixing this, and the commit for each. source
| Introduced | Fixed in | Commit |
|---|---|---|
| 7.1 | 7.1.5 | b06730c6af58 |
| 7.1 | 7.2 | 8b97b302f553 |
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:LAttack vector, local
- The bug is reached only when the legacy fs/ntfs driver parses a crafted $INDEX_ROOT during mount or local VFS inode load (ntfs_fill_super→ntfs_iget/ntfs_index_iget→ntfs_read_locked_inode or ntfs_read_locked_index_inode); there is no network-facing handler.
- AC:LAttack complexity, low
- The attacker fully controls on-disk $INDEX_ROOT header geometry (value_length, entries_offset, index_length, allocated_size), so the missing checks and resulting out-of-bounds access in ntfs_lookup_inode_by_name are reliably triggerable with no race or uncontrollable layout dependency.
- PR:NPrivileges required, none
- The attacker needs no account or capabilities on the victim—only a malicious NTFS image presented via USB, loop device, or dual-boot partition that root, udisks2, or automount loads on their behalf.
- UI:NUser interaction, none
- On kiosks, desktops, and automotive/embedded systems that automount removable NTFS media, inserting the device alone runs ntfs_fill_super and inode read of directory/index metadata with no further deliberate victim action beyond presenting the volume.
- S:UScope, unchanged
- Impact is confined to kernel heap parsing within the same OS security authority; this is not a VM escape, IOMMU bypass, or cross-sandbox boundary crossing.
- C:HConfidentiality impact, high
- Without full header validation, crafted entries_offset/index_length pairs let ntfs_lookup_inode_by_name and inode-read paths read past the resident $INDEX_ROOT value into adjacent kmalloc MFT/slab memory, enabling unbounded kernel information disclosure.
- I:HIntegrity impact, high
- The same unchecked header fields drive index entry walks and later RW index memmove/insert paths on a writable mount; attacker-controlled geometry can corrupt heap metadata beyond the resident value, yielding a write primitive suitable for privilege escalation.
- A:HAvailability impact, high
- Out-of-bounds reads of index entries and header fields from malformed $INDEX_ROOT during mount or directory access can fault on unmapped memory and oops/panic the kernel, fully denying availability.