CVE-2026-97439

What the bug is

[BUG] A corrupted ntfs3 image can hit a NULL function pointer call in generic_perform_write() after toggling system.ntfs_attrib and then overwriting system.dos_attrib on the same file. BUG: kernel NULL pointer dereference, address: 0000000000000000 \#PF: supervisor instruction fetch in kernel mode \#PF: error_code(0x0010) - not-present page PGD bed5067 P4D bed5067 PUD 0 Oops: Oops: 0010 [#1] SMP KASAN NOPTI RIP: 0010:0x0 Code: Unable to access opcode bytes at 0xffffffffffffffd6. RSP: 0018:ffff88801025f988 EFLAGS: 00010246 Call Trace: generic_perform_write+0x409/0x8c0 mm/filemap.c:4255 __generic_file_write_iter+0x1bb/0x200 mm/filemap.c:4372 ntfs_file_write_iter+0xcd9/0x1c20 fs/ntfs3/file.c:1253 new_sync_write fs/read_write.c:593 [inline] vfs_write+0x63b/0xf70 fs/read_write.c:686 ksys_write+0x133/0x250 fs/read_write.c:738 __do_sys_write fs/read_write.c:749 [inline] __se_sys_write fs/read_write.c:746 [inline] __x64_sys_write+0x77/0xc0 fs/read_write.c:746 ... [CAUSE] system.ntfs_attrib updates ATTR_DATA flags via ni_new_attr_flags() and switches i_mapping->a_ops to ntfs_aops_cmpr when FILE_ATTRIBUTE_COMPRESSED is set. system.dos_attrib then overwrites ni->std_fa from a one-byte DOS attribute value, clearing the compression bit without updating ATTR_DATA or the mapping operations. Old buffered writes use is_compressed(ni) to choose __generic_file_write_iter(). That leaves generic_perform_write() calling a NULL write_begin callback from ntfs_aops_cmpr. [FIX] Treat system.dos_attrib as a low-byte DOS attribute update and preserve the existing non-DOS attribute bits in ni->std_fa. This keeps compressed and sparse state consistent with ATTR_DATA and the mapping operations while keeping the existing DOS attribute semantics intact.

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/xattr.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 ntfs3

Prints 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

2026-09-24 (24 days ago)source

CVSS

no vector published, unrated

Attack vector

not published

EPSS

0.17%, higher than 6.2% 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	5.15.222	533217b90add
5.15	6.1.189	f2d6bc89e223
5.15	6.6.158	fdc9f65aa663
5.15	6.12.111	2de91ae285b0
5.15	6.18.53	407ee19828a7
5.15	7.2	b1c1101067d9

Debian advisories