CVE-2026-89781 fs/ntfs3: fix out-of-bounds read in read_log_rec_buf()
A crafted NTFS image triggers an out-of-bounds read in the Linux kernel NTFS3 driver, potentially leaking memory or causing a crash.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-89781?
CVE-2026-89781 is a high-severity memory corruption vulnerability in Linux, published on 16 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: fix out-of-bounds read in read_log_rec_buf()
read_log_rec_buf() copies a log record into a caller buffer starting at
u32 off = lsn_to_page_off(log, lsn) + log->record_header_len;
log->record_header_len (and log->data_off, used for the following pages) comes verbatim from the on-disk restart area and is only checked for 8-byte alignment in is_rst_area_valid(), so off can exceed log->page_size. "tail = log->page_size - off" then underflows and memcpy() reads past the page_size-sized buffer returned by read_log_page(), spilling adjacent slab memory into the replay buffer.
This is reachable by mounting a crafted NTFS image:
BUG: KASAN: slab-out-of-bounds in read_log_rec_buf+0x216/0x580 Read of size 64 at addr ffff88800a877ff8 by task exploit/127 read_log_rec_buf fs/ntfs3/fslog.c:2299 log_replay fs/ntfs3/fslog.c:4216 ntfs_loadlog_and_replay fs/ntfs3/fsntfs.c:324 ntfs_fill_super fs/ntfs3/super.c:1392 get_tree_bdev_flags fs/super.c:1694 __x64_sys_mount fs/namespace.c:4360 The buggy address is located 4088 bytes to the right of the 4096-byte region [ffff88800a876000, ffff88800a877000)
Reject an in-page offset outside the current page before the copy.
[almaz.alexandrovich@paragon-software.com: replaced the >= sign with >]
Which versions are affected by CVE-2026-89781?
How do I fix CVE-2026-89781?
Apply the vendor's patch.
Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.
Is CVE-2026-89781 being exploited?
There is no known exploitation of CVE-2026-89781 in the wild and no public exploit code.
Sources
Also known as AZL-101192, BELL-CVE-2026-89781, DEBIAN-CVE-2026-89781, GHSA-xf98-5fqf-rh4f, UBUNTU-CVE-2026-89781.