CVE-2026-72191: ntfs3: validate split-point offset in indx_insert_into_buffer
In the Linux kernel, the following vulnerability has been resolved:
ntfs3: validate split-point offset in indxinsertintobuffer
indxinsertintobuffer() computes
used = used1 - tocopy - spsize; memmove(det, Add2Ptr(sp, spsize), used - le32tocpu(hdr1->deoff));
where sp and spsize come from hdrfindsplit(). hdrfindsplit() walks entries by le16tocpu(e->size) without validating that each step stays within hdr->used or that the size field is at least sizeof(struct NTFSDE). indexhdrcheck(), the on-load gatekeeper, only validates header-level fields (used, total, deoff) and does not walk per-entry sizes.
A crafted NTFS image whose leaf INDEXHDR reports used == total but contains one interior NTFSDE with size = 0xFFF0 therefore passes validation, descends to indxinsertintobuffer() through the ntfscreate() -> indxinsertentry() path, and makes hdrfindsplit() return an sp whose spsize (0xFFF0) greatly exceeds the remaining bytes in the buffer. The u32 subtraction underflows and the memmove count becomes a near-4-GiB value, producing an out-of-bounds kernel write that corrupts adjacent allocations and panics the kernel.
Reproduced on 7.0.0-rc7 with UML + KASAN via a crafted image and a single 'touch' inside the mounted directory; crash site resolves to fs/ntfs3/index.c at the memmove. Trigger requires only local mount of an attacker-supplied filesystem image (USB, loopback, or removable media auto-mount).
Reject the split whenever the chosen sp plus its declared size already extends past hdr1->used. This is the minimal fix; it preserves the existing hdrfindsplit() contract and relies on the same out: cleanup path as the pre-existing error returns.
A prior OOB read in the very same indxinsertintobuffer() memmove was fixed in commit b8c44949044e ("fs/ntfs3: Fix OOB read in indxinsertintobuffer") by tightening hdrfinde(), but that fix does not cover the split-point size field path addressed here: sp is returned by hdrfindsplit(), not hdrfinde(), and the underflow is driven by sp->size rather than hdr->used exceeding hdr->total.
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
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ubuntu/linuxto a version that resolves this vulnerability.Fixed in 6.8.0-147.147 - Upgrade
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ubuntu/linux-awsto a version that resolves this vulnerability.Fixed in 6.8.0-1067.70 - Upgrade
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ubuntu/linux-aws-7.0to a version that resolves this vulnerability.Fixed in 7.0.0-1013.13~24.04.1 - Upgrade
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ubuntu/linux-azureto a version that resolves this vulnerability.Fixed in 6.8.0-1071.79 - Upgrade
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ubuntu/linux-azure-7.0to a version that resolves this vulnerability.Fixed in 7.0.0-1017.17~24.04.1 - Upgrade
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ubuntu/linux-azure-fdeto a version that resolves this vulnerability.Fixed in 6.8.0-1069.76 - Upgrade
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ubuntu/linux-azure-fde-7.0to a version that resolves this vulnerability.Fixed in 7.0.0-1016.16~24.04.1 - Upgrade
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ubuntu/linux-gcpto a version that resolves this vulnerability.Fixed in 6.8.0-1071.79 - Upgrade
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ubuntu/linux-gcp-7.0to a version that resolves this vulnerability.Fixed in 7.0.0-1013.13~24.04.1 - Upgrade
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ubuntu/linux-gketo a version that resolves this vulnerability.Fixed in 6.8.0-1066.74 - Upgrade
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ubuntu/linux-gkeopto a version that resolves this vulnerability.Fixed in 6.8.0-1052.56 - Upgrade
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ubuntu/linux-hwe-7.0to a version that resolves this vulnerability.Fixed in 7.0.0-34.34~24.04.1 - Upgrade
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ubuntu/linux-ibmto a version that resolves this vulnerability.Fixed in 6.8.0-1067.68 - Upgrade
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ubuntu/linux-lowlatencyto a version that resolves this vulnerability.Fixed in 6.8.0-147.147.1 - Upgrade
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ubuntu/linux-nvidia-tegrato a version that resolves this vulnerability.Fixed in 6.8.0-1035.38 - Upgrade
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ubuntu/linux-oracleto a version that resolves this vulnerability.Fixed in 6.8.0-1064.67 - Upgrade
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ubuntu/linux-oracle-7.0to a version that resolves this vulnerability.Fixed in 7.0.0-1012.12~24.04.1 - Upgrade
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ubuntu/linux-riscv-7.0to a version that resolves this vulnerability.Fixed in 7.0.0-34.34.1~24.04.1 - Upgrade
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ubuntu/linux-bluefieldto a version that resolves this vulnerability.Fixed in 6.8.0-1033.38 - Upgrade
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ubuntu/linux-realtimeto a version that resolves this vulnerability.Fixed in 6.8.1-1062.63 - Upgrade
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ubuntu/linux-aws-fipsto a version that resolves this vulnerability.Fixed in 6.8.0-1067.70+fips1 - Upgrade
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ubuntu/linux-azure-fipsto a version that resolves this vulnerability.Fixed in 6.8.0-1071.79+fips1 - Upgrade
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ubuntu/linux-fipsto a version that resolves this vulnerability.Fixed in 6.8.0-147.147+fips1 - Upgrade
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ubuntu/linux-gcp-fipsto a version that resolves this vulnerability.Fixed in 6.8.0-1071.79+fips1 - Upgrade
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ubuntu/linuxto a version that resolves this vulnerability.Fixed in 7.0.0-34.34 - Upgrade
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ubuntu/linux-awsto a version that resolves this vulnerability.Fixed in 7.0.0-1013.13 - Upgrade
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ubuntu/linux-azureto a version that resolves this vulnerability.Fixed in 7.0.0-1017.17 - Upgrade
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ubuntu/linux-azure-fdeto a version that resolves this vulnerability.Fixed in 7.0.0-1016.16 - Upgrade
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ubuntu/linux-gcpto a version that resolves this vulnerability.Fixed in 7.0.0-1013.13 - Upgrade
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ubuntu/linux-gketo a version that resolves this vulnerability.Fixed in 7.0.0-1007.8 - Upgrade
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ubuntu/linux-ibmto a version that resolves this vulnerability.Fixed in 7.0.0-1014.14 - Upgrade
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ubuntu/linux-oem-7.0to a version that resolves this vulnerability.Fixed in 7.0.0-1014.14 - Upgrade
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ubuntu/linux-oracleto a version that resolves this vulnerability.Fixed in 7.0.0-1012.12 - Upgrade
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ubuntu/linux-raspito a version that resolves this vulnerability.Fixed in 7.0.0-1020.20 - Upgrade
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ubuntu/linux-realtimeto a version that resolves this vulnerability.Fixed in 7.0.0-34.34.1 - Upgrade
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ubuntu/linux-riscvto a version that resolves this vulnerability.Fixed in 7.0.0-34.34.1 - Compensating control
In fs/ntfs3/index.c, update indx_insert_into_buffer() to reject the split when the selected split point plus its declared size extends past hdr1->used, before performing the memmove; use the existing out: cleanup path for the error return.
Event History
Frequently Asked Questions
What is the severity of CVE-2026-72191?
CVE-2026-72191 has a risk score of 72, indicating a medium to high severity level.
How do I fix CVE-2026-72191?
To fix CVE-2026-72191, update to the latest version of the Linux kernel that includes the resolution for this vulnerability.
What type of vulnerability is CVE-2026-72191?
CVE-2026-72191 is a memory handling vulnerability in the Linux kernel's NTFS3 file system driver.
Is CVE-2026-72191 exploitable remotely?
The exploitability of CVE-2026-72191 depends on the specific configurations and use-cases of affected systems.
Which versions of the Linux kernel are affected by CVE-2026-72191?
The specific versions affected by CVE-2026-72191 can be determined by referencing the changes introduced in the kernel updates released after August 15, 2026.