CVE-2026-72210: ntfs: fix off-by-one in mapping pairs decoding bounds checks
In the Linux kernel, the following vulnerability has been resolved:
ntfs: fix off-by-one in mapping pairs decoding bounds checks
In ntfs_mapping_pairs_decompress(), attr_end points one byte past the
end of the attribute record:
attr_end = (u8 *)attr + le32_to_cpu(attr->length);
The two bounds checks validating that mapping pair data bytes fit within
the attribute use strict greater-than (>), which allows a one-byte
out-of-bounds read when the data extends exactly to attr_end:
b = *buf & 0xf;
if (b) {
if (unlikely(buf + b > attr_end)) // off-by-one
goto io_error;
for (deltaxcn = (s8)buf[b--]; b; b--)
deltaxcn = (deltaxcn << 8) + buf[b];
}
When buf + b == attr_end, the check evaluates to false and buf[b] reads
one byte past the valid attribute boundary. The same pattern appears in
the LCN delta bytes check.
Fix both checks to use >= so that buf[b] at exactly attr_end is
correctly rejected as out of bounds.
Security readout for executives and security teams
Plain-English summary
A Linux NTFS filesystem parser can read one byte beyond a valid attribute boundary when decoding specially formed mapping data. Systems are exposed when affected kernels process NTFS content. Although rated critical in the supplied record, the sources establish an out-of-bounds read but do not demonstrate code execution, remote reachability, or broader impact.
Executive priority
Treat as an urgent patch-validation issue on systems that process untrusted NTFS content. Do not infer internet-wide remote compromise from the 9.8 score alone: the supplied technical evidence describes a parser over-read, while practical impact and exploitability remain unproven. Prioritize exposed workloads, then validate vendor backports across the remaining Linux estate.
Technical view
In ntfs_mapping_pairs_decompress(), two checks used > instead of >= against attr_end. When buf plus the decoded field length equals attr_end, subsequent indexing reads one byte outside the attribute record. The referenced stable-kernel changes correct both checks. The supplied affected-version data identifies Linux 7.1 through 7.1.5 and 7.2, but its version formatting is ambiguous.
Likely exposure
Prioritize Linux systems running the listed affected versions that enable NTFS support and process NTFS filesystems, disk images, or removable media. Exposure through network services is not established by the technical description, despite the supplied CVSS network vector. The record marks other listed versions as unaffected, but distribution-specific backports require vendor confirmation.
Exploitation context
The supplied record says this issue is not in KEV and provides no evidence of active exploitation or a public proof of concept. Triggering requires the vulnerable NTFS decoder to encounter boundary-reaching mapping-pair data. Whether this can produce consequences beyond a one-byte read is not established by the sources.
Researcher notes
The defect is a pair of boundary-condition errors in mapping-pair decoding. Changing > to >= rejects indexing exactly at attr_end. Important uncertainties remain: no CWE is supplied, affected-version notation is inconsistent, and the CVSS confidentiality, integrity, availability, and network claims are not substantiated by the included technical narrative. No exploitability evidence is provided.
Mitigation direction
Apply a vendor-supported kernel update containing the referenced bounds-check correction.
Check distribution advisories for backported fixes and authoritative affected-version guidance.
Until updated, restrict affected systems from processing untrusted NTFS media or disk images.
Follow vendor guidance if operational constraints prevent immediate kernel replacement.
Validation and detection
Inventory kernel versions and identify systems with NTFS filesystem support enabled.
Confirm the installed kernel includes either applicable referenced stable fix or a vendor backport.
Review whether affected hosts process removable NTFS media, disk images, or externally supplied filesystems.
After updating, verify the patched kernel is running and document any required reboot.
Monitor vendor advisories for corrected version ranges or revised impact information.
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Potential ATT&CK relevance
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CVSS vector scores
1 official score
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