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CVE-2026-80598
ntfs3: fix out-of-bounds read in decompress_lznt
Published 2026-08-28 (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-2026-80598 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
decompress_lznt() does not validate array index bounds before accessing the decompression table. A corrupted NTFS3 image with invalid compressed data can trigger an out-of-bounds read. Add index bounds checking to prevent the OOB access.
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/lznt.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
- 2026-08-28 (2 months ago)source
- CVSS
- 7.8 high
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:Hsource recompute it - Attack vector
- local (AV:L)source
- EPSS
- 0.18%, higher than 6.6% 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 | 1113fa5b01a4 |
| 5.15 | 6.1.178 | 61415ffa365d |
| 5.15 | 6.6.145 | bd77afca2ae9 |
| 5.15 | 6.12.97 | c694f8ea2611 |
| 5.15 | 6.18.40 | ff05a98150eb |
| 5.15 | 7.1.5 | a93980141253 |
| 5.15 | 7.2 | 7160a57192fb |
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
- decompress_lznt() is reached only when the kernel reads LZNT-compressed NTFS file data through local VFS paths (read/mmap/write on compressed files) after an ntfs3 mount; it is not invoked from network protocol parsers such as nfsd, ksmbd, or the TCP/IP stack.
- AC:LAttack complexity, low
- Attacker fully controls the on-disk LZNT compressed stream in a crafted file/image and can reliably drive the index past s_max_off[] bounds to trigger the out-of-bounds read; syzbot/syzkaller reproduced this without races or attacker-uncontrollable memory layout.
- PR:LPrivileges required, low
- Triggering decompression requires only read access to a compressed file via open/read/mmap, or mounting a malicious NTFS image which needs CAP_SYS_ADMIN obtainable by unprivileged users inside user+mount namespaces on typical Linux systems.
- UI:NUser interaction, none
- No separate victim action is required when the attacker has local access: they can mount a crafted NTFS image in a user namespace and read the malicious compressed file themselves to reach decompress_lznt() without anyone else interacting with the system.
- S:UScope, unchanged
- The flaw corrupts or discloses kernel memory during NTFS LZNT decompression within the same kernel security domain; it does not cross VM, container, or IOMMU boundaries and is not a sandbox or hypervisor escape.
- C:HConfidentiality impact, high
- The bug performs out-of-bounds reads of kernel memory past the nine-element s_max_off[] table in .rodata, and attacker-controlled index values feed parse_pair() and decompression output, enabling disclosure of sensitive kernel data into page-cache buffers returned to userspace.
- I:HIntegrity impact, high
- Unbounded index growth from malformed LZNT input passes attacker-influenced shift widths into parse_pair(), producing malformed backreference offset/length pairs that drive the LZ copy loop and can corrupt kernel page-cache memory in ways chainable toward arbitrary write primitives.
- A:HAvailability impact, high
- Out-of-bounds access to s_max_off[] is a kernel memory safety violation that KASAN/KFENCE report and can oops or panic the kernel; repeated reads of a malicious compressed file can reliably deny service to the reading process or the entire system.