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CVE-2026-89779
fs/ntfs3: validate ef->size covers the record's name and value
Published 2026-09-16 (33 days ago) by the Linux kernel CNA. Subsystem fs/ntfs3. Debian urgency: not yet assigned.
What to do, per Debian release
Debian's own status for CVE-2026-89779 in every release this site tracks, and what each one means in practice. Every status below is the one the Debian Security Team publishes for this CVE. source
| Release | Status | Version | What this means |
|---|---|---|---|
| Debian 12bookworm | fixedDLA-4841-1 · 2026-10-17 · text | 6.1.190-1 | Update the kernel and reboot. DLA-4841-1 shipped the fix on 2026-10-17, in 6.1.190-1. A running kernel keeps the old code until the machine restarts. |
| Debian 13trixie | fixedDSA-6528-1 · 2026-09-29 · text | 6.12.111-1 | Update the kernel and reboot. DSA-6528-1 shipped the fix on 2026-09-29, in 6.12.111-1. A running kernel keeps the old code until the machine restarts. |
| Debian 14forky | fixed | 7.2.6-1 | Update the kernel and reboot. Fixed in 7.2.6-1. A running kernel keeps the old code until the machine restarts. |
| Debian unstablesid | fixed | 7.2.6-1 | Update the kernel and reboot. Fixed in 7.2.6-1. A running kernel keeps the old code until the machine restarts. |
| Debian 12bookworm · linux-6.12 | fixedDLA-4817-1 · 2026-10-04 · text | 6.12.111-1~deb12u1 | Update the kernel and reboot. DLA-4817-1 shipped the fix on 2026-10-04, in 6.12.111-1~deb12u1. A running kernel keeps the old code until the machine restarts. |
The vulnerability
What the bug is
When an EA record has a non-zero ef->size, ntfs_read_ea() only checks that the record fits in the remaining buffer (ea_size > bytes), not that ef->size is large enough to hold the record's own name_len + 1 + elength. A crafted image can pass validation with, e.g., ef->size = 24 but elength = 0xffff. ntfs_get_ea() then trusts elength and copies it out of the undersized record, reading past the kmalloc(info->size) allocation and leaking heap memory to userspace via getxattr(): BUG: KASAN: slab-out-of-bounds in ntfs_get_ea (fs/ntfs3/xattr.c:302) Read of size 65535 at addr ffff888100794550 by task exploit __asan_memcpy (mm/kasan/shadow.c:105) ntfs_get_ea (fs/ntfs3/xattr.c:302) ntfs_getxattr (fs/ntfs3/xattr.c:848) __vfs_getxattr (fs/xattr.c:441) vfs_getxattr (fs/xattr.c:474) do_getxattr (fs/xattr.c:800) path_getxattrat (fs/xattr.c:868) do_syscall_64 (arch/x86/entry/syscall_64.c:94) The buggy address is located 80 bytes inside of allocated 84-byte region in cache kmalloc-96 Compute the size the record needs and require ef->size to cover it.
Where it lives
The fix touches these files. If the subsystem is one you do not use, the practical exposure is lower, though the package is still the vulnerable one.
fs/ntfs3/xattr.c
- What this is
- NTFS3 FILESYSTEMMAINTAINERS section matched on fs/ntfs3/ · ntfs3@lists.linux.dev · Supported
- Kernel module
- ntfs3
Check it on the machine
grep -w CONFIG_NTFS3_FS /boot/config-$(uname -r)Reads the booted kernel's own configuration, on the machine and nowhere else. =y is built in, =m is a module, and an is not set line means the code is not there.
lsmod | grep -w ntfs3Prints a line if that module is loaded right now, and nothing if it is not. One that is not loaded can still be loaded later by anything that needs it.
Show whether Debian builds this, per release
Debian does not build this code in 3 releases. It does build it in 2 releases, so the answer depends on which release the machine runs.
- bookwormn
- trixiem
- forky, sidn
- bookworm · linux-6.12m
- n
- not enabled on any flavour - this release does not build the code
- m
- a loadable module on every flavour - check lsmod, can be blacklisted
- Build switch
- CONFIG_NTFS3_FS
From the configuration Debian publishes for every kernel flavour it builds. It covers only the architectures Debian ships a linux-config package for, and nothing about a kernel you built yourself. Debian's own status above stays authoritative about the source package.MAINTAINERS kbuild Makefiles Debian linux-config packages
Signals
- Published
- 2026-09-16 (33 days ago)source
- CVSS
- 9.1 critical
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:Hsource recompute it - Attack vector
- network (AV:N)source
- EPSS
- 0.70%, higher than 52.1% of all CVEssource
- CISA KEV
- not listedthe KEV catalogue
- Debian urgency
- not yet assignedsource
- Subsystem
- fs/ntfs3
Upstream fixes
The versions the CNA records as introducing and fixing this, and the commit for each. source
| Introduced | Fixed in | Commit |
|---|---|---|
| 5.15.121 | 5.15.221 | b27e68ad818a |
| 6.1.40 | 6.1.188 | 28a924c7e67e |
| 6.2 | 6.6.157 | d585ed083089 |
| 6.2 | 6.12.110 | 077df8464cf2 |
| 6.2 | 6.18.52 | aab1880058ac |
| 6.2 | 7.2.6 | c8a109c9e23a |
| 6.2 | 7.3 | c22f91d82cb9 |
Debian advisories
| Advisory | Date | Shipped to | Debian |
|---|---|---|---|
| DLA-4841-1 | 2026-10-17 | bookworm 6.1.190-1 | tracker |
| DLA-4817-1 | 2026-10-04 | bookworm 6.12.111-1~deb12u1 | tracker |
| DSA-6528-1 | 2026-09-29 | trixie 6.12.111-1 | tracker |
Why the CNA scored it this way
Quoted from the kernel CNA's own scoring file, word for word. A highlighted metric carries the most severe value CVSS v3.1 defines for it, which is what pushes the score up. source
- AV:NAttack vector, network
- ntfs3 registers export_operations and an empty-prefix xattr handler, so ksmbd SMB2 QUERY_INFO FILE_FULL_EA and nfsd GETXATTR reach vfs_getxattr→ntfs_getxattr→ntfs_get_ea on an exported NTFS volume; a crafted EA named user.* is listed and returned over the network on NAS/hybrid SMB/NFS servers.
- AC:LAttack complexity, low
- The attacker fully controls on-disk EA_FULL fields; ef->size=24 with elength=0xffff passes ntfs_read_ea() and makes ntfs_get_ea() memcpy 65535 bytes past the kmalloc(info->size) object deterministically, with no race or attacker-uncontrollable layout.
- PR:NPrivileges required, none
- The leak needs only read access to a file carrying the crafted EA: a ksmbd guest/anonymous client with FILE_READ_EA, an NFSv4 AUTH_SYS/guest GETXATTR, or automount of attacker media, with no local account or CAP_SYS_ADMIN on the host.
- UI:NUser interaction, none
- After the NTFS volume is mounted and exported—the normal state for NAS, dual-boot, and automounted removable NTFS—the attacker issues SMB QUERY_INFO, NFS GETXATTR, or getxattr(2) themselves; no further victim clicks, prompts, or confirmations are required.
- S:UScope, unchanged
- The slab over-read and heap leak occur in the host kernel ntfs3 xattr path under a single security authority; this is standard filesystem exploitation, not a VM escape, IOMMU/DMA bypass, or other cross-boundary breakout.
- C:HConfidentiality impact, high
- ntfs_get_ea() copies attacker-chosen elength (up to 65535) bytes from past the kmalloc(info->size) EA buffer into the getxattr output that VFS, ksmbd, and nfsd return to the caller; a ~64KiB kernel-heap leak to userspace or a remote SMB/NFS client is Confidentiality High.
- I:NIntegrity impact, none
- The destination is sized from the probed elength (ksmbd/nfsd) or the caller-supplied size with an explicit len>size ERANGE check, so this is a source over-read into a bounds-checked xattr buffer, not an out-of-bounds write, UAF, or control-flow hijack primitive.
- A:HAvailability impact, high
- KASAN reports a 65535-byte slab-out-of-bounds read in ntfs_get_ea from an 84-byte kmalloc-96 object; that unbounded heap over-read can fault unmapped adjacent slab pages and oops or panic the kernel, which is Availability High.