# CVE-2026-89611

## Summary

- **CVE ID:** CVE-2026-89611
- **Severity:** CRITICAL
- **CVSS Score:** 9.8 (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H)
- **CWE:** N/A
- **Published:** Sep 11, 2026
- **Last Modified:** Sep 13, 2026

## Description

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

ntfs: validate non-resident attribute offsets

ntfs_attr_update_meta() shifts the attribute name when converting between
non-sparse and sparse attributes. Converting to sparse also adds the
compressed_size field before the name and mapping pairs, requiring eight
additional bytes in the attribute record.

However, the validator does not check that name_offset is within safe
boundaries for these operations or that the additional space is available.
A malicious MFT record could set name_offset such that:

1. The name is positioned at the very end of a non-sparse attribute.
   Converting to sparse would shift the name forward by 8 bytes,
   writing beyond the attribute boundary.

2. The name overlaps with the mapping pairs, causing corruption during
   conversion.

Add validation to ensure:
- For named attributes, name_offset is within valid bounds
- Name does not extend beyond the attribute or overlap with mapping pairs
- For non-sparse, non-compressed attributes, eight bytes are available
  after mapping_pairs_offset for the compressed_size field

The space check also covers unnamed attributes, for which name_offset = 0
is valid and no name range needs to be checked.

## Affected Products

- Linux — Linux (1da177e4c3f41524e886b7f1b8a0c1fc7321cac2)
- Linux — Linux (0)
- Linux — Linux (7.2.4)
- Linux — Linux (7.3-rc1)

## References

- [CNA](https://git.kernel.org/stable/c/cd7b3dc7557faadeea626034e3bac68a449851ef)
- [CNA](https://git.kernel.org/stable/c/a83e82b0ec3ae523028e24813f23f18b43e8fc1c)

## Exploitation Prediction (EPSS)

- **EPSS Score:** 0.38%
- **EPSS Percentile:** 31.6

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_Exported from OnDuty AI Vulnerability Intelligence on 2026-09-17._