CVE-2026-72211 ntfs: grow index root value before reparent header update
A logic error in the Linux kernel NTFS driver can cause filesystem corruption and denial of service during index root reparenting operations.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-72211?
CVE-2026-72211 is a critical denial of service vulnerability in Linux, published on 15 Aug 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:
ntfs: grow index root value before reparent header update
ntfs_ir_reparent() moves the resident index root entries into an index block and leaves a small root stub containing the child VCN. That root stub can be larger than the existing resident value. For example, an empty root with value_length 48 has an index area of 32 bytes, while the large-index root stub needs index_length and allocated_size of 40 bytes.
The current code publishes the larger index.index_length and index.allocated_size before resizing the resident value. If the resize returns -ENOSPC, the recovery path can call ntfs_inode_add_attrlist(), which looks attributes up again while the root header says allocated_size 40 but the resident value still only provides 32 bytes of index area. Lookup-time $INDEX_ROOT validation then correctly rejects that transient layout as corrupt.
This reproduces as a generic/013 failure under qemu. In the failing run, the transient root had value_len=48, index_size=32, index_length=40, and allocated_size=40, and ntfsprogs-plus ntfsck reported "Corrupt index root in MFT record 1177".
When the root stub grows, resize the resident value before publishing the larger root header. If the resize fails, the old root remains valid for recovery lookups. Keep the existing header-before-resize ordering for shrink or same-size cases so the resident value never temporarily exposes an allocated_size beyond its bounds.
Which versions are affected by CVE-2026-72211?
How do I fix CVE-2026-72211?
Apply the vendor's patch.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2026-72211 being exploited?
There is no known exploitation of CVE-2026-72211 in the wild and no public exploit code.
Sources
Also known as DEBIAN-CVE-2026-72211, GHSA-mw2v-m8cx-mx72, UBUNTU-CVE-2026-72211.