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CVE-2026-90132
ntfs: reject unprivileged writes to reserved $LX* xattrs
Published 2026-09-17 (31 days ago) by the Linux kernel CNA. Subsystem fs/ntfs. Debian urgency: unimportant.
What to do, per Debian release
Debian's own status for CVE-2026-90132 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 | not affected | 6.1.190-1 | Nothing to do. bookworm never shipped the vulnerable code. |
| Debian 13trixie | not affected | 6.12.113-1 | Nothing to do. trixie never shipped the vulnerable code. |
| 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. |
The vulnerability
What the bug is
Reject setxattr of the reserved $LXUID, $LXGID, $LXMOD and $LXDEV names from userspace unless the caller has CAP_SYS_ADMIN.
Where it lives
The fix touches these files. If the subsystem is one you do not use, the practical exposure is lower, though the package is still the vulnerable one.
fs/ntfs/ea.c
- What this is
- NTFS FILESYSTEMMAINTAINERS section matched on fs/ntfs/ · linux-fsdevel@vger.kernel.org · Maintained
- Kernel module
- ntfs
Check it on the machine
grep -w CONFIG_NTFS_FS /boot/config-$(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 ntfsPrints 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 builds this as a loadable module. Every release with an answer below compiles it as a module on every flavour, so whether the code is in the running kernel depends on whether that module is loaded. The build rule could not be established for 2 releases, so nothing is claimed about those.
- bookworm, trixie?
- forky, sidm
- ?
- not established - no Makefile entry for the affected file
- m
- a loadable module on every flavour - check lsmod, can be blacklisted
Where a release above reads "not established", no build rule for the affected file was found in that release's kernel tree. That is a gap in this lookup, not a finding that the code is absent.
- Build switch
- CONFIG_NTFS_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
- 2026-09-17 (31 days ago)source
- CVSS
- 7.1 high
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:Nsource recompute it - Attack vector
- local (AV:L)source
- EPSS
- 0.16%, higher than 5.1% of all CVEssource
- CISA KEV
- not listedthe KEV catalogue
- Debian urgency
- unimportantsource
- Subsystem
- fs/ntfs
Upstream fixes
The versions the CNA records as introducing and fixing this, and the commit for each. source
| Introduced | Fixed in | Commit |
|---|---|---|
| 7.1 | 7.2.6 | 86f46508016b |
| 7.1 | 7.3 | ea6a67ef6445 |
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:LAttack vector, local
- The attacker-controlled $LXUID/$LXGID/$LXMOD/$LXDEV name and 4-byte value enter via setxattr/fsetxattr/lsetxattr into ntfs_setxattr(); ksmbd SMB2 SET_INFO and nfsd4_decode_xattr_name both prefix user., so those paths cannot store the unprefixed EAs that ntfs_ea_get_wsl_inode() loads.
- AC:LAttack complexity, low
- ntfs_setxattr() persists the EAs through ntfs_set_ea() without changing live i_uid/i_mode; the attacker then drops refs and forces icache reclaim so ntfs_read_locked_inode() runs ntfs_ea_get_wsl_inode() and applies the planted uid and S_ISUID mode. No uninfluenced race is required.
- PR:LPrivileges required, low
- xattr_permission() only requires inode_permission(MAY_WRITE) for these unprefixed names, and pre-fix ntfs_setxattr() had no capable() check. Default ntfs mounts leave vol->uid INVALID_UID (so $LXUID is applied) and files mode 0777, so any unprivileged writer can set the EAs.
- UI:NUser interaction, none
- The attacker issues setxattr on a file they can already write on an ntfs volume that is already mounted; no other user must insert media, mount an image, or open the planted file.
- S:UScope, unchanged
- ntfs_ea_get_wsl_inode() copies planted $LXUID/$LXMOD into the host inode's i_uid and i_mode. That is local privilege escalation inside the same kernel authority, not a VM, IOMMU, or sandbox escape.
- C:HConfidentiality impact, high
- On reload, ntfs_ea_get_wsl_inode() does i_uid_write() from $LXUID and assigns inode->i_mode from $LXMOD; planting uid 0 and S_ISUID on an executable the attacker wrote yields euid 0 and full disclosure of host files.
- I:HIntegrity impact, high
- The same $LXUID/$LXMOD plant lets the attacker execute their own binary as root after ntfs_read_locked_inode() reloads the inode, giving unrestricted modification of host data. The bug is an unauthorized write of kernel-trusted WSL permission EAs.
- A:NAvailability impact, none
- ntfs_set_ea() of $LXUID/$LXGID/$LXMOD/$LXDEV only stores NTFS extended attributes, and ntfs_ea_get_wsl_inode() only assigns i_uid, i_gid, i_mode, and rdev. That path has no kernel crash, hang, UAF, or BUG_ON.