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

fs/ntfs3: reject out-of-range evcn in mi_enum_attr()

In mi_enum_attr(), the start/end VCN validation for non-resident
attributes is:

if (svcn > evcn + 1) goto out;

When evcn is U64_MAX the "evcn + 1" expression wraps to 0 and any svcn
passes the check. For evcn values close to U64_MAX (but not equal to it)
the right-hand side is still a meaningless near-wrap upper bound, so a
malformed on-disk attribute with svcn == 0 and evcn near U64_MAX can pass
mi_enum_attr() unrejected.

VCN (virtual cluster number) is a cluster index, so any valid evcn is
bounded by the volume's total cluster count, which ntfs3 holds in
sbi->used.bitmap.nbits (set up in ntfs_init_from_boot() before any caller
of mi_enum_attr() runs). Reject evcn values that fall outside this range.

However, an empty non-resident attribute (no allocated clusters) is
legitimately encoded with svcn == 0 and evcn == -1 (U64_MAX), e.g. via
attr->nres.evcn = cpu_to_le64((u64)vcn - 1) with vcn == 0. That sentinel
must keep passing, so exclude evcn == U64_MAX from the range check. The
existing "svcn > evcn + 1" test still tolerates the sentinel ("0 > 0" is
false) and continues to require svcn == 0 for it, while the range check
rejects every other out-of-range evcn and thereby also defuses the
"evcn + 1" wraparound.

svcn does not need its own bound: once evcn < nbits, "svcn > evcn + 1"
implies svcn <= nbits.

[almaz.alexandrovich@paragon-software.com: fixed evcn check]

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Source ID Title
Debian DLA Debian DLA DLA-4817-1 linux-6.12 security update
Debian DSA Debian DSA DSA-6528-1 linux security update
Fixes

Solution

No solution given by the vendor.


Workaround

No workaround given by the vendor.

History

Sun, 20 Sep 2026 02:00:00 +0000

Type Values Removed Values Added
Weaknesses CWE-190
CWE-20

Fri, 18 Sep 2026 21:30:00 +0000

Type Values Removed Values Added
Metrics cvssV3_1

{'score': 7.8, 'vector': 'CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H'}


Thu, 17 Sep 2026 16:30:00 +0000

Type Values Removed Values Added
Description In the Linux kernel, the following vulnerability has been resolved: fs/ntfs3: reject out-of-range evcn in mi_enum_attr() In mi_enum_attr(), the start/end VCN validation for non-resident attributes is: if (svcn > evcn + 1) goto out; When evcn is U64_MAX the "evcn + 1" expression wraps to 0 and any svcn passes the check. For evcn values close to U64_MAX (but not equal to it) the right-hand side is still a meaningless near-wrap upper bound, so a malformed on-disk attribute with svcn == 0 and evcn near U64_MAX can pass mi_enum_attr() unrejected. VCN (virtual cluster number) is a cluster index, so any valid evcn is bounded by the volume's total cluster count, which ntfs3 holds in sbi->used.bitmap.nbits (set up in ntfs_init_from_boot() before any caller of mi_enum_attr() runs). Reject evcn values that fall outside this range. However, an empty non-resident attribute (no allocated clusters) is legitimately encoded with svcn == 0 and evcn == -1 (U64_MAX), e.g. via attr->nres.evcn = cpu_to_le64((u64)vcn - 1) with vcn == 0. That sentinel must keep passing, so exclude evcn == U64_MAX from the range check. The existing "svcn > evcn + 1" test still tolerates the sentinel ("0 > 0" is false) and continues to require svcn == 0 for it, while the range check rejects every other out-of-range evcn and thereby also defuses the "evcn + 1" wraparound. svcn does not need its own bound: once evcn < nbits, "svcn > evcn + 1" implies svcn <= nbits. [almaz.alexandrovich@paragon-software.com: fixed evcn check]
Title fs/ntfs3: reject out-of-range evcn in mi_enum_attr()
First Time appeared Linux
Linux linux Kernel
CPEs cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
Vendors & Products Linux
Linux linux Kernel
References

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cve-icon MITRE

Status: PUBLISHED

Assigner: Linux

Published:

Updated: 2026-10-19T08:59:35.489Z

Reserved: 2026-09-11T19:38:34.792Z

Link: CVE-2026-90199

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Received

Published: 2026-09-17T17:17:14.790

Modified: 2026-10-19T09:19:09.927

Link: CVE-2026-90199

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-09-20T01:45:17Z

Weaknesses