CVE-2026-64432 fs/ntfs3: validate Dirty Page Table capacity in log_replay copy_lcns
A crafted NTFS image triggers a slab out-of-bounds write in the Linux kernel NTFS3 driver during mount, potentially allowing code execution or system crash.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Local or same network only
- Victim action needed
- A user has to click or open something
- Fix
- Available
What is CVE-2026-64432?
CVE-2026-64432 is a high-severity memory corruption vulnerability in Linux kernel, published on 25 Jul 2026. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link.
Official description
In the Linux kernel, the following vulnerability has been resolved:
fs/ntfs3: validate Dirty Page Table capacity in log_replay copy_lcns
In the analysis pass of $LogFile journal replay, log_replay() copies LCNs from each action log record into an existing Dirty Page Table (DPT) entry without bounding the destination index. A crafted NTFS image with DPT entry lcns_follow=1 and an action log record with lcns_follow=2 produces a kernel slab out-of-bounds write at mount time:
BUG: KASAN: slab-out-of-bounds in log_replay+0x654c/0xdb60 Write of size 8 at addr ffff8880095e1040 by task mount
Two attacker-controlled fields can drive j+i past the allocated page_lcns[] array:
1. dp->lcns_follow (capacity) can be smaller than lrh->lcns_follow. 2. lrh->target_vcn may be smaller than dp->vcn, making the u64 subtraction wrap to a huge size_t.
Validate target VCN delta and per-record LCN count against the DPT entry capacity, bail via the existing out: cleanup label with -EINVAL.
This mirrors the bounds-check pattern added in commit b2bc7c44ed17 ("fs/ntfs3: Fix slab-out-of-bounds read in DeleteIndexEntryRoot") and commit 0ca0485e4b2e ("fs/ntfs3: validate rec->used in journal-replay file record check").
Weakness: CWE-787
Which versions are affected by CVE-2026-64432?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2026-64432?
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-2026-64432 being exploited?
There is no known exploitation of CVE-2026-64432 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as BELL-CVE-2026-64432, DEBIAN-CVE-2026-64432, GHSA-4xg7-26qr-mccf, ROOT-OS-DEBIAN-12-CVE-2026-64432, ROOT-OS-UBUNTU-2204-CVE-2026-64432, UBUNTU-CVE-2026-64432.