UBUNTU-CVE-2026-99101: Medium severity ubuntu/linux vulnerability
In the Linux kernel, the following vulnerability has been resolved: ntfs: move attribute payload before shrinking its record ntfsnewattrflags() 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.
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Compensating control
In ntfs_new_attr_flags(), move the non-resident attribute payload—including its name and mapping pairs—to the shorter-header offsets before shrinking the attribute record when compression or sparse state is cleared; retain the existing resize-before-move ordering when growing the record.
Event History
Frequently Asked Questions
What filesystem activity can trigger the corruption?
The issue is triggered when compression or sparse state is cleared on a non-resident NTFS attribute, causing its record header to shrink. Re-enabling compression on an empty file can then persist malformed mapping pairs.
How can administrators identify evidence of this issue?
An affected NTFS filesystem may be reported by ntfsck as having a missing or invalid run length. The malformed mapping-pairs array is persisted when compression is re-enabled on an empty file.
Which Ubuntu kernel packages are listed as affected?
The affected software list includes ubuntu/linux, ubuntu/linux-fips, ubuntu/linux-aws, ubuntu/linux-azure, ubuntu/linux-gcp, ubuntu/linux-aws-fips, ubuntu/linux-azure-fips, and ubuntu/linux-gcp-fips.