CVE-2026-72202 ntfs: avoid heap allocation for free-cluster readahead state
A memory allocation failure in the Linux kernel NTFS driver can cause indefinite blocking of processes waiting for free cluster counts, leading to denial of service.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-72202?
CVE-2026-72202 is a high-severity 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: avoid heap allocation for free-cluster readahead state
get_nr_free_clusters() allocates a temporary file_ra_state before it publishes the precomputed free cluster count, sets NVolFreeClusterKnown(), and wakes vol->free_waitq. If that allocation fails, the worker returns without setting the flag or waking waiters, so callers waiting for the free count can block indefinitely.
The readahead state is only used synchronously while scanning the bitmap. Keep it on the stack and pass it by address to the readahead helper. This eliminates the early allocation failure path instead of adding a special case that publishes a conservative count and wakes the waitqueue. Zero-initialize the on-stack state because file_ra_state_init() only sets ra_pages and prev_pos.
Apply the same treatment to __get_nr_free_mft_records(), which scans the MFT bitmap with the same short-lived readahead state.
Which versions are affected by CVE-2026-72202?
How do I fix CVE-2026-72202?
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-2026-72202 being exploited?
There is no known exploitation of CVE-2026-72202 in the wild and no public exploit code.
Sources
Also known as DEBIAN-CVE-2026-72202, GHSA-r757-m3xv-cw84, UBUNTU-CVE-2026-72202.