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CVE-2026-72197
fs/ntfs3: bound DeleteIndexEntryAllocation memmove length
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-2026-72197 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
In do_action()'s DeleteIndexEntryAllocation case, e->size comes from an on-disk INDEX_BUFFER entry. When e->size makes e + e->size point past hdr + hdr->used, PtrOffset(e1, Add2Ptr(hdr, used)) returns a negative ptrdiff_t that is silently cast to a quasi-infinite size_t when passed to memmove(). The memmove then walks past the destination buffer. The sibling DeleteIndexEntryRoot case at fslog.c:3540-3543 already carries the corresponding guard: if (PtrOffset(e1, Add2Ptr(hdr, used)) < esize || Add2Ptr(e, esize) > Add2Ptr(lrh, rec_len) || used + esize > le32_to_cpu(hdr->total)) { goto dirty_vol; } Apply the same shape to the allocation-path case. Also reject esize == 0: memmove(e, e, ...) is a no-op and leaves hdr->used unchanged, hiding a malformed entry from the existing check_index_header() walk. Reproduced under UML+KASAN on mainline 8d90b09e6741 by mounting a crafted NTFS image: the unguarded memmove takes a length of 0xffffffffffffff00 and the kernel oopses in memmove+0x81/0x1a0 on the do_action+0x36a2 frame. [almaz.alexandrovich@paragon-software.com: clang-formatted the changes]
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/fslog.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
- 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 7.6% 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 | c38ed2ab62fa |
| 5.15 | 6.1.178 | b509b9613f20 |
| 5.15 | 6.6.145 | 4c8aac931c1c |
| 5.15 | 6.12.97 | f383aae59ec3 |
| 5.15 | 6.18.40 | 09fddd52c1b0 |
| 5.15 | 7.1.5 | 554700c65d39 |
| 5.15 | 7.2 | fc4626bb3656 |
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
- Reachable only by mounting attacker-controlled NTFS media via the local mount syscall path (path_mount→ntfs_fill_super→ntfs_loadlog_and_replay→log_replay→do_action); ntfs3 parses on-disk $LogFile redo records, not remote network packets.
- AC:LAttack complexity, low
- The attacker fully controls crafted $LogFile DeleteIndexEntryAllocation redo data and INDEX_BUFFER entry sizes on disk, so the PtrOffset underflow to ~0xffffffffffffff00 and subsequent memmove OOB are deterministic with no race or uncontrollable layout preconditions.
- PR:NPrivileges required, none
- No privileges on the target are required; exploitation only needs a malicious NTFS image presented to ntfs3 (USB/loop/NBD block device) that root, udisks2/systemd automount, or an image-handling service mounts, matching the kernel CNA model for crafted-filesystem bugs.
- UI:NUser interaction, none
- On desktops/kiosks/automotive systems where udisks2 or systemd automounts removable NTFS media, inserting or attaching the crafted image triggers log_replay during mount with no further deliberate victim action beyond routine media handling.
- S:UScope, unchanged
- The quasi-infinite memmove corrupts kernel heap memory within the host OS security authority during ntfs3 journal replay; this is standard kernel memory corruption, not a VM escape, IOMMU bypass, or other cross-boundary scope change.
- C:HConfidentiality impact, high
- The unchecked memmove length (~0xffffffffffffff00) performs a massive out-of-bounds read from beyond the kmalloc INDEX_BUFFER scratch buffer, exposing adjacent slab/heap contents and satisfying OOB-read/arbitrary-disclosure guidance even though KASAN reports an oops in memmove.
- I:HIntegrity impact, high
- The same memmove writes far past the destination INDEX_BUFFER allocation in kernel heap, yielding a large out-of-bounds write primitive that can corrupt adjacent kernel objects and be leveraged for control-flow hijacking or privilege escalation.
- A:HAvailability impact, high
- Reproduced by mounting a crafted NTFS image under UML+KASAN, the unbounded memmove oopses the kernel in memmove from do_action; such heap corruption reliably threatens panic/oops and full denial of service on mount.