In the Linux kernel, the following vulnerability has been resolved: fs/ntfs3: fix missing run load for vcn0 in attr_data_get_block_locked() When a compressed or sparse attribute has its clusters frame-aligned, vcn is rounded down to the frame start using cmask, which can result in vcn != vcn0. In this case, vcn and vcn0 may reside in different attribute segments. The code already handles the case where vcn is in a different segment by loading its runs before allocation. However, it fails to load runs for vcn0 when vcn0 resides in a different segment than vcn. This causes run_lookup_entry() to return SPARSE_LCN for vcn0 since its segment was never loaded into the in-memory run list, triggering the WARN_ON(1). Fix this by adding a missing check for vcn0 after the existing vcn segment check. If vcn0 falls outside the current segment range [svcn, evcn1), find and load the attribute segment containing vcn0 before performing the run lookup. The following scenario triggers the bug: attr_data_get_block_locked() vcn = vcn0 & cmask <- vcn != vcn0 after frame alignment load runs for vcn segment <- vcn0 segment not loaded! attr_allocate_clusters() <- allocation succeeds run_lookup_entry(vcn0) <- vcn0 not in run -> SPARSE_LCN WARN_ON(1) <- bug fires here!

A flaw was found in the Linux kernel's `fs/ntfs3` component. When handling compressed or sparse attributes with frame-aligned clusters, a missing run load for `vcn0` can occur if `vcn0` resides in a different attribute segment. This oversight can lead to a kernel warning (`WARN_ON(1)`) during a run lookup, potentially causing system instability or a Denial of Service (DoS). A local user could trigger this condition.

Red Hat Enterprise Linux 10 Not affected kernel Red Hat Enterprise Linux 6 Not affected kernel Red Hat Enterprise Linux 7 Not affected kernel Red Hat Enterprise Linux 7 Not affected kernel-rt Red Hat Enterprise Linux 8 Not affected kernel Red Hat Enterprise Linux 8 Not affected kernel-rt Red Hat Enterprise Linux 9 Not affected kernel Red Hat Enterprise Linux 9 Not affected kernel-rt https://www.cve.org/CVERecord?id=CVE-2026-53027 https://nvd.nist.gov/vuln/detail/CVE-2026-53027 https://lore.kernel.org/linux-cve-announce/2026062453-CVE-2026-53027-fbe3@gregkh/T