CVE-2026-80869 ntfs: bound the attribute-list entry in ntfs_read_inode_mount()
A crafted NTFS image can cause an out-of-bounds read in the Linux kernel during mount, potentially disclosing memory contents to local attackers.
- 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-2026-80869?
CVE-2026-80869 is a vulnerability in Linux, published on 4 Sep 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:
ntfs: bound the attribute-list entry in ntfs_read_inode_mount()
The $MFT attribute-list walk in ntfs_read_inode_mount() validates each entry only with "(u8 *)al_entry + 6 > al_end" and "(u8 *)al_entry + le16_to_cpu(al_entry->length) > al_end", but then reads al_entry->lowest_vcn (an __le64 at offset 8) and al_entry->mft_reference (offset 16) -- fields beyond the 6 bytes proven in range. al_entry->length is attacker-controlled and only required non-zero, so a short entry (e.g. length 8) placed at the tail passes both checks while the lowest_vcn / mft_reference reads fall past al_end.
al_end is ni->attr_list + attr_list_size (the on-disk size); the buffer is kvzalloc(round_up(attr_list_size, SECTOR_SIZE)), so the sector rounding usually absorbs the over-read -- but when attr_list_size is a multiple of SECTOR_SIZE there is no slack and a crafted $MFT attribute list produces an out-of-bounds read at mount time.
Validate the entry with ntfs_attr_list_entry_is_valid() (added in patch 1/3) before dereferencing it, matching the bound the other attribute-list walks now use. The validator already requires the length to cover the fixed header, which makes the separate "!al_entry->length" check redundant, so drop it too.
Which versions are affected by CVE-2026-80869?
How do I fix CVE-2026-80869?
Apply the vendor's patch.
Is CVE-2026-80869 being exploited?
There is no known exploitation of CVE-2026-80869 in the wild and no public exploit code.
Sources
Also known as DEBIAN-CVE-2026-80869, GHSA-3w59-j737-r4rc, UBUNTU-CVE-2026-80869.