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CVE-2026-72188
ntfs: sanitize MFT references returned from ntfs_lookup_inode_by_name()
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-2026-72188 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
ntfs_lookup_inode_by_name() returns MFT references read from directory index entries on disk. These values are untrusted, but the function can currently return an error-marked MFT reference to its callers without validating it. Callers later decode lookup failures with MREF_ERR(). A crafted NTFS image can set the MREF error bit while leaving the low bits as an arbitrary value, causing callers to consume a bogus pseudo-errno instead of treating the lookup result as corrupted on-disk metadata. Fix this at the source by normalizing every error-marked MFT reference returned from ntfs_lookup_inode_by_name() to ERR_MREF(-EIO). Apply this to all four directory lookup return paths so every caller gets a validated result without needing additional checks or an API change. This keeps the sanitization in the common lookup helper, which is cleaner than duplicating validation in each caller.
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/dir.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
- 9.1 critical
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:Hsource recompute it - Attack vector
- network (AV:N)source
- EPSS
- 0.50%, higher than 41.6% 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 | 83f396d881c4 |
| 7.1 | 7.2 | d97a36bae86a |
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
- fs/ntfs registers ntfs_export_ops; remote nfsd/ksmbd LOOKUP/OPEN/stat on an exported crafted NTFS volume reaches ntfs_lookup→ntfs_lookup_inode_by_name parsing attacker-controlled INDX indexed_file values without local shell access.
- AC:LAttack complexity, low
- The attacker fully controls on-disk directory index indexed_file MFT references and can set the ERR_MREF error bit with arbitrary low bits; decoding the forged pseudo-errno via MREF_ERR() is deterministic from a crafted image with no race or external timing.
- PR:NPrivileges required, none
- Triggering needs only a malicious NTFS image (USB, loop, dual-boot disk) mounted by the host or lookup access to exported NTFS paths via NFS/SMB; no init-namespace root or CAP_SYS_ADMIN is required on the code path that consumes the bogus errno.
- UI:NUser interaction, none
- fill_super mount-time lookups (hiberfil.sys, $Quota) and subsequent local or remote path lookups call ntfs_lookup_inode_by_name as soon as the crafted volume is mounted or exported, without further per-attack cooperation beyond volume presentation.
- S:UScope, unchanged
- Forged errno handling perturbs VFS lookup and mount safety decisions within the host kernel/filesystem authority only; this is standard filesystem parsing abuse, not a VM escape, IOMMU bypass, or cross-security-boundary scope change.
- C:NConfidentiality impact, none
- The flaw only mis-decodes error-marked MFT references into attacker-chosen errno values returned to callers; there is no out-of-bounds read, use-after-free, or other kernel memory disclosure primitive.
- I:HIntegrity impact, high
- Spoofing -ENOENT via error-bit indexed_file can add negative dentries for present index entries and make check_windows_hibernation_status/load_and_init_quota treat hiberfil.sys/$Quota as absent, bypassing hibernation/quota guards and permitting rw corruption of live Windows hibernation and NTFS metadata.
- A:HAvailability impact, high
- Hibernation-check bypass allows rw I/O on a suspended Windows volume, corrupting hiberfil.sys and preventing resume; forged lookup errnos also leave persistent negative-cache and index inconsistencies that can render the volume or dependent OS unusable.