CVE-2026-64357

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

xfs: fix exchmaps reservation limit check

xfs_exchmaps_estimate_overhead() adds the bmbt and rmapbt overhead to a local resblks variable, but the final UINT_MAX check still tests req->resblks. That is the reservation value from before the overhead was added.

The computed value is stored back in req->resblks and later passed to xfs_trans_alloc(), whose block reservation argument is unsigned int. Check the computed reservation so the existing limit applies to the value that will be used.

This vulnerability is rated as Moderate severity for Red Hat Enterprise Linux because it requires local access with unprivileged user permissions to trigger the flaw, limiting the blast radius to a local denial of service. The issue affects environments utilizing the XFS file system where range-exchange operations calculate transaction block allocations incorrectly. While XFS is widely deployed across Red Hat platforms, an attacker cannot exploit this defect over the network or gain unauthorized privileges.

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.