CVE-2026-89616 fs/ntfs3: fix info-leak on partial LZNT decompress in ni_read_frame()
A local attacker can read uninitialized kernel memory via a crafted NTFS file, potentially leaking kernel pointers and defeating KASLR.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-89616?
CVE-2026-89616 is a high-severity vulnerability in Linux, published on 11 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
In the Linux kernel, the following vulnerability has been resolved:
fs/ntfs3: fix info-leak on partial LZNT decompress in ni_read_frame()
ni_read_frame() decompresses an LZNT $DATA frame into the vmapped target pages and then trusts decompress_lznt()'s return value:
unc_size = decompress_lznt(frame_ondisk, ondisk_size, frame_mem, frame_size); if ((ssize_t)unc_size < 0) err = unc_size; else if (!unc_size || unc_size > frame_size) err = -EINVAL;
decompress_lznt() stops as soon as the compressed stream is exhausted (e.g. a zero chunk header) and returns the number of bytes it actually wrote, which may be far less than frame_size. The bytes between unc_size and frame_size are never written. The only memset() that follows zeroes the region beyond i_valid; when the frame lies entirely within the file's valid size that memset() does not run, so the gap retains whatever was in the just-vmapped pages. All pages are then marked uptodate and returned to userspace, disclosing uninitialized (recently-freed) kernel page memory. A crafted compressed file whose stream decompresses to only a few bytes leaks the remainder of every frame on a plain read(2), which is enough to recover kernel pointers and defeat KASLR.
Zero the [unc_size, frame_size) tail immediately after a successful LZNT decompress so the remainder reads back as zero.
Which versions are affected by CVE-2026-89616?
How do I fix CVE-2026-89616?
Apply the vendor's patch.
Is CVE-2026-89616 being exploited?
There is no known exploitation of CVE-2026-89616 in the wild and no public exploit code.
Sources
Also known as AZL-100632, BELL-CVE-2026-89616, DEBIAN-CVE-2026-89616, GHSA-486v-9mj8-37c6, UBUNTU-CVE-2026-89616.