CVE-2026-72478 fs/ntfs3: add bounds check to run_get_highest_vcn()
A missing bounds check in the Linux kernel NTFS3 driver allows out-of-bounds reads during mount, potentially causing crashes or leaking memory.
- 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-2026-72478?
CVE-2026-72478 is a high-severity memory corruption vulnerability in Linux, published on 15 Aug 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: add bounds check to run_get_highest_vcn()
run_get_highest_vcn() parses a packed NTFS mapping-pairs buffer without any length bound, relying solely on a 0x00 terminator to stop. A crafted $LogFile UpdateMappingPairs record whose embedded attribute contains mapping-pairs runs without a terminator causes the function to read past the slab allocation, triggering a KASAN slab-out-of-bounds read on mount.
The sibling function run_unpack() received an analogous bounds-check in commit b62567bca474 ("ntfs3: add buffer boundary checks to run_unpack()"), but run_get_highest_vcn() was missed.
Take a run_buf_size parameter and reject any run header whose payload would extend past the buffer end, mirroring the pattern used by run_unpack(). The caller in fslog.c passes the remaining attribute bytes after the mapping-pairs offset.
KASAN report (on mainline v7.1 merge window HEAD):
BUG: KASAN: slab-out-of-bounds in run_get_highest_vcn+0x3c0/0x410 Read of size 1 at addr ffff88800e2d5400 by task mount/72 Call Trace: run_get_highest_vcn+0x3c0/0x410 do_action.isra.0+0x3ba8/0x7b50 log_replay+0x9ddd/0x10200 ntfs_loadlog_and_replay+0x4ad/0x610 ntfs_fill_super+0x214a/0x4540
Which versions are affected by CVE-2026-72478?
How do I fix CVE-2026-72478?
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-2026-72478 being exploited?
There is no known exploitation of CVE-2026-72478 in the wild and no public exploit code.
Sources
Also known as BELL-CVE-2026-72478, DEBIAN-CVE-2026-72478, GHSA-pcrg-m6wx-53ch, UBUNTU-CVE-2026-72478.