Improper Handling of Missing Special Element Affecting kernel6.18-tools-debuginfo package, versions <1:6.18.39-79.141.amzn2023


Severity

Recommended
high

Based on Amazon Linux security rating.

Threat Intelligence

EPSS
0.12% (3rd percentile)

Do your applications use this vulnerable package?

In a few clicks we can analyze your entire application and see what components are vulnerable in your application, and suggest you quick fixes.

Test your applications
  • Snyk IDSNYK-AMZN2023-KERNEL618TOOLSDEBUGINFO-18907617
  • published18 Aug 2026
  • disclosed24 Jun 2026

Introduced: 24 Jun 2026

CVE-2026-53027  (opens in a new tab)
CWE-166  (opens in a new tab)

How to fix?

Upgrade Amazon-Linux:2023 kernel6.18-tools-debuginfo to version 1:6.18.39-79.141.amzn2023 or higher.
This issue was patched in ALAS2023-2026-2045.

NVD Description

Note: Versions mentioned in the description apply only to the upstream kernel6.18-tools-debuginfo package and not the kernel6.18-tools-debuginfo package as distributed by Amazon-Linux. See How to fix? for Amazon-Linux:2023 relevant fixed versions and status.

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!

CVSS Base Scores

version 3.1