CVE-2026-80530

A flaw was found in the Linux kernel's XFS filesystem. When performing file range exchanges with the XFS_EXCHMAPS_INO1_WRITTEN flag set, the reflink flag can be prematurely cleared from an inode that still manages shared written data. This can lead to data corruption between files that share data through the reflink mechanism, as subsequent writes may bypass Copy-on-Write (CoW) protection.

XFS exchange-range handling can incorrectly clear the reflink inode flag when XFS_EXCHMAPS_INO1_WRITTEN is used and hole or unwritten mappings from file1 are skipped. As a result, an inode may retain shared written extents while no longer being marked as reflinked. Subsequent writes to that inode can bypass the CoW path and modify the underlying shared blocks in place, thereby altering data visible through other reflink-related files. This is a filesystem integrity and access-control violation, not a kernel memory-corruption primitive.

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.

To mitigate this issue, prevent module xfs from being loaded. Please see https://access.redhat.com/solutions/41278 for how to blacklist a kernel module to prevent it from loading automatically.