CVE-2026-98139 ntfs: only count successfully cleared runs when freeing clusters

Medium 5.5 Published Updated

A logic error in the Linux kernel NTFS driver incorrectly counts failed cluster frees, corrupting free space tracking and potentially causing denial of service.

Exploited in the wild
Not known
Login needed
Any signed-in user
Attackable
Local or same network only
Victim action needed
Not needed
Fix
Available

What is CVE-2026-98139?

CVE-2026-98139 is a medium-severity vulnerability in Linux kernel, published on 25 Sep 2026. It can only be exploited from the same machine or local network, with no action from the victim.

Official description

In the Linux kernel, the following vulnerability has been resolved:

ntfs: only count successfully cleared runs when freeing clusters

ntfs_cluster_free_from_rl_nolock() adds a run's length to nr_freed whenever the error bookkeeping condition is false, which includes cases where ntfs_bitmap_clear_run() actually failed - e.g. a second run failing with the same errno as an earlier one, or any failure after a non-ENOMEM error was already recorded. Since a failed ntfs_bitmap_clear_run() rolls back its partial modifications, no bits were cleared for that run, yet its length still inflates vol->free_clusters, corrupting statfs output and the allocator's free space gate.

Only count runs whose bitmap clear succeeded.

Which versions are affected by CVE-2026-98139?

It affects 1 product.

Products include Linux kernel.

How do I fix CVE-2026-98139?

Apply the vendor's patch.

Is CVE-2026-98139 being exploited?

There is no known exploitation of CVE-2026-98139 in the wild and no public exploit code.

All Linux kernel vulnerabilities

Sources

Also known as DEBIAN-CVE-2026-98139, GHSA-6rpr-wqmr-68rh, UBUNTU-CVE-2026-98139.

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