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CVE-2026-89616
fs/ntfs3: fix info-leak on partial LZNT decompress in ni_read_frame()
Published 2026-09-11 (37 days 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-2026-89616 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 | fixedDLA-4841-1 · 2026-10-17 · text | 6.1.190-1 | Update the kernel and reboot. DLA-4841-1 shipped the fix on 2026-10-17, in 6.1.190-1. A running kernel keeps the old code until the machine restarts. |
| Debian 13trixie | fixedDSA-6528-1 · 2026-09-29 · text | 6.12.111-1 | Update the kernel and reboot. DSA-6528-1 shipped the fix on 2026-09-29, in 6.12.111-1. A running kernel keeps the old code until the machine restarts. |
| Debian 14forky | fixed | 7.2.6-1 | Update the kernel and reboot. Fixed in 7.2.6-1. A running kernel keeps the old code until the machine restarts. |
| Debian unstablesid | fixed | 7.2.6-1 | Update the kernel and reboot. Fixed in 7.2.6-1. A running kernel keeps the old code until the machine restarts. |
| Debian 12bookworm · linux-6.12 | fixedDLA-4817-1 · 2026-10-04 · text | 6.12.111-1~deb12u1 | Update the kernel and reboot. DLA-4817-1 shipped the fix on 2026-10-04, in 6.12.111-1~deb12u1. A running kernel keeps the old code until the machine restarts. |
The vulnerability
What the bug is
ni_read_frame() decompresses an LZNT $DATA frame into the vmapped target pages and then trusts decompress_lznt()'s return value: unc_size = decompress_lznt(frame_ondisk, ondisk_size, frame_mem, frame_size); if ((ssize_t)unc_size < 0) err = unc_size; else if (!unc_size || unc_size > frame_size) err = -EINVAL; decompress_lznt() stops as soon as the compressed stream is exhausted (e.g. a zero chunk header) and returns the number of bytes it actually wrote, which may be far less than frame_size. The bytes between unc_size and frame_size are never written. The only memset() that follows zeroes the region beyond i_valid; when the frame lies entirely within the file's valid size that memset() does not run, so the gap retains whatever was in the just-vmapped pages. All pages are then marked uptodate and returned to userspace, disclosing uninitialized (recently-freed) kernel page memory. A crafted compressed file whose stream decompresses to only a few bytes leaks the remainder of every frame on a plain read(2), which is enough to recover kernel pointers and defeat KASLR. Zero the [unc_size, frame_size) tail immediately after a successful LZNT decompress so the remainder reads back as zero.
Where it lives
The fix touches these files. If the subsystem is one you do not use, the practical exposure is lower, though the package is still the vulnerable one.
fs/ntfs3/frecord.c
- What this is
- NTFS3 FILESYSTEMMAINTAINERS section matched on fs/ntfs3/ · ntfs3@lists.linux.dev · Supported
- Kernel module
- ntfs3
Check it on the machine
grep -w CONFIG_NTFS3_FS /boot/config-$(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 2 releases, so the answer depends on which release the machine runs.
- bookwormn
- trixiem
- forky, sidn
- bookworm · linux-6.12m
- 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
- 2026-09-11 (37 days ago)source
- CVSS
- 7.5 high
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:Nsource recompute it - Attack vector
- network (AV:N)source
- EPSS
- 0.41%, higher than 34.4% 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 | 5.15.221 | 7d60a4c49af4 |
| 5.15 | 6.1.188 | cd40eee4923d |
| 5.15 | 6.6.157 | 77d8efd04745 |
| 5.15 | 6.12.109 | 0f699ddb290a |
| 5.15 | 6.18.50 | 376ee45659a4 |
| 5.15 | 7.2.4 | 4a1b39b2e10e |
| 5.15 | 7.3 | 35d1ea92c7d9 |
Debian advisories
| Advisory | Date | Shipped to | Debian |
|---|---|---|---|
| DLA-4841-1 | 2026-10-17 | bookworm 6.1.190-1 | tracker |
| DLA-4817-1 | 2026-10-04 | bookworm 6.12.111-1~deb12u1 | tracker |
| DSA-6528-1 | 2026-09-29 | trixie 6.12.111-1 | tracker |
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
- ni_read_frame() runs from ntfs_read_folio on LZNT-compressed reads. ntfs3 registers export_operations, so ksmbd/nfsd vfs_read and splice on an exported NTFS volume reach this path and return leaked page-cache bytes to a remote SMB/NFS client on NAS and hybrid file-server deployments.
- AC:LAttack complexity, low
- A crafted NTFS image fully controls the on-disk LZNT stream; a zero chunk header makes decompress_lznt() return far fewer than frame_size bytes deterministically, with no race, rare config, or attacker-uncontrollable memory layout required.
- PR:NPrivileges required, none
- A remote client can trigger the leak by reading a world-readable compressed file over NFS (AUTH_SYS/guest) or a ksmbd guest share with no local account or capability on the host; ntfs3 file-read paths check only inode state, not privileges.
- UI:NUser interaction, none
- After the NTFS volume is mounted and exported—the normal state for NAS, dual-boot, and automounted removable NTFS—the attacker only issues reads; no further victim action such as opening a file or confirming a prompt is required.
- S:UScope, unchanged
- The leak exposes the host kernel's own freed page contents through that kernel's page cache to the reader and does not cross a VM, guest-to-host, IOMMU, or other security-authority boundary.
- C:HConfidentiality impact, high
- Each crafted frame can disclose up to the uncompressed LZNT unit (typically 64KiB) of uninitialized recently-freed kernel page memory, repeatable across the file, including kernel pointers for KASLR bypass and residual secrets rather than a small bounded read.
- I:NIntegrity impact, none
- The defect only leaves the decompressed-frame tail unzeroed in the file's own page-cache pages; it does not perform an out-of-bounds write, corrupt kernel objects, or yield a write or control-flow hijack primitive.
- A:NAvailability impact, none
- Partial LZNT decompress is treated as success; pages are marked uptodate and the read returns data without a kernel oops, panic, hang, deadlock, or other availability loss.