CVE-2026-97439 fs/ntfs3: preserve non-DOS attribute bits in system.dos_attrib
A local attacker can cause a kernel crash via a NULL pointer dereference in the ntfs3 filesystem driver by manipulating file attributes.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-97439?
CVE-2026-97439 is a vulnerability in Linux, published on 24 Sep 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
In the Linux kernel, the following vulnerability has been resolved:
fs/ntfs3: preserve non-DOS attribute bits in system.dos_attrib
[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.
Which versions are affected by CVE-2026-97439?
How do I fix CVE-2026-97439?
Apply the vendor's patch.
Is CVE-2026-97439 being exploited?
There is no known exploitation of CVE-2026-97439 in the wild and no public exploit code.
Sources
Also known as AZL-103625, BELL-CVE-2026-97439, DEBIAN-CVE-2026-97439, GHSA-rc9g-r7vc-2qq2, UBUNTU-CVE-2026-97439.