Bug 2532167 (CVE-2026-89611)

Summary: CVE-2026-89611 kernel: ntfs: validate non-resident attribute offsets
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security <prodsec-ir-bot>
Status: NEW --- QA Contact:
Severity: medium Docs Contact:
Priority: medium    
Version: unspecifiedCC: akhatavk, aos-team-art-private, asdas, dpaolell, jdelft, jupierce, lgarciaa, mbiarnes, ppalepu, ppostler, prdhamdh, rhel-process-autobot, sghai, sidsharm, suppawar, vlaad, watson-tool-maintainers
Target Milestone: ---Keywords: Security
Target Release: ---   
Hardware: All   
OS: Linux   
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A flaw was found in the Linux kernel. The NTFS file system driver does not properly validate non-resident attribute offsets when converting between sparse and non-sparse attributes. A local attacker could craft a malicious Master File Table (MFT) record, which could lead to writing data beyond allocated memory boundaries or overlapping with other critical data. This memory corruption could result in a denial of service (DoS) or system instability.
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Description OSIDB Bzimport 2026-09-11 21:04:26 UTC 
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.
Comment 1 Keith Grant 2026-09-18 19:04:08 UTC 
Upstream advisory:
https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-89611.mbox