---
id: "CVE-2026-99101"
kind: "vulnerability"
aliases: ["CVE-2026-99101"]
title: "Linux kernel NTFS: attribute move corrupts mapping pairs when compression toggles"
severity: "unknown"
cvss: null
epss: null
exploited: false
status: "open"
category: "runtime"
products: []
ecosystems: []
tags: ["kernel", "linux", "ntfs", "runtime"]
not_affected_if: []
published_at: "2026-10-28T11:17:29+00:00"
first_seen_at: "2026-10-28T11:32:34+00:00"
updated_at: "2026-10-28T11:37:53+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-99101", "first_seen_at": "2026-10-28T11:32:34+00:00"}]
---

# Linux kernel NTFS: attribute move corrupts mapping pairs when compression toggles

When the Linux kernel's NTFS driver clears compression or sparse state on a file, it resizes the attribute record before moving its payload, so the following attribute's bytes get copied into the mapping pairs. Re-enabling compression on an empty file then writes a malformed mapping pairs array to disk that ntfsck reports as a bad run length.

_Summary, check and fix written by a model from the sources; labelled as such._

## Timeline

- 2026-10-28T11:32:34+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-99101

## From the sources

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

ntfs: move attribute payload before shrinking its record

ntfs_new_attr_flags() resizes the non-resident attribute record before
moving its name and mapping pairs to their shorter-header offsets when
compression or sparse state is cleared.

Shrinking the record first moves the following attribute over the tail of
the old record. The subsequent memmove() therefore copies bytes from that
following attribute instead of the old mapping pairs. Re-enabling
compression on an empty file persists those bytes as a malformed mapping
pairs array, which ntfsck reports as a missing or invalid run length.

Move the payload before shrinking the record, while retaining the existing
resize-before-move ordering when growing it.

---

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