CVE-2026-97547 xfs: fix exchange-range reflink flag clearing issue with INO1_WRITTEN
- Exploited in the wild
- Not known
- Fix
- Available
What is CVE-2026-97547?
CVE-2026-97547 is a vulnerability in Linux, published on 25 Sep 2026.
Official description
In the Linux kernel, the following vulnerability has been resolved:
xfs: fix exchange-range reflink flag clearing issue with INO1_WRITTEN
When exchanging two full-file ranges, xmi_can_exchange_reflink_flags() can move the reflink inode flag from the file that currently has it to the other file, as long as exactly one side is marked. This assumes that the file contents, and therefore all shared extents, are exchanged.
That assumption is not true when XFS_EXCHMAPS_INO1_WRITTEN is set. xfs_exchmaps_can_skip_mapping() can skip hole and unwritten mappings from file1, so an exchange can complete without moving every mapping that the earlier flag-swap decision accounted for. In that case the post-operation cleanup can clear the reflink flag from an inode that still owns shared written extents. Later writes then take the non-reflink write path and may update blocks that should still have been protected by CoW, which shows up as data corruption between reflink-related files.
Fix this by disabling the reflink flag exchange whenever XFS_EXCHMAPS_INO1_WRITTEN is requested. The contents exchange can still proceed; the conservative outcome is that both inodes keep the reflink flag. The regular reflink flag cleanup path can drop the extra flag later once the inode no longer has shared extents.
Which versions are affected by CVE-2026-97547?
How do I fix CVE-2026-97547?
Upgrade to a fixed version.
Is CVE-2026-97547 being exploited?
There is no known exploitation of CVE-2026-97547 in the wild and no public exploit code.
Sources
Also known as BELL-CVE-2026-97547, DEBIAN-CVE-2026-97547, GHSA-cpgc-625w-fgr3, UBUNTU-CVE-2026-97547.