# CVE-2026-72199: ntfs: validate resident index root values on lookup

> Missing validation of NTFS index root headers can cause kernel crashes, requiring a patch to enforce alignment and size invariants.

- **Severity:** Critical 9.8 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 15 Aug 2026
- **Updated:** 18 Aug 2026
- **Also known as:** DEBIAN-CVE-2026-72199, GHSA-r953-ww6g-j7cw, UBUNTU-CVE-2026-72199

## What is CVE-2026-72199?

CVE-2026-72199 is a critical vulnerability in Linux, published on 15 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

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

ntfs: validate resident index root values on lookup

Resident $INDEX_ROOT values carry index header fields that callers
consume after lookup. Some callers already validate parts of the layout
before walking entries, but those checks are scattered and do not cover
all root header invariants, such as entries_offset alignment and lower
bound, index_length, and allocated_size consistency.

The resident root resize paths now keep these header fields consistent
while the value size changes: ntfs_ir_truncate() lowers
index.allocated_size before shrinking the resident value, and
ntfs_ir_reparent() grows the resident value before publishing a larger
root header. Lookup-time validation can therefore cover these invariants
without tripping over the driver's own resize paths.

Add $INDEX_ROOT to the minimum resident value size table and validate the
resident index header fields before returning the attribute from lookup.
Require 8-byte aligned index header fields, a sane entries_offset, an
index_length within allocated_size, allocated_size within the resident
value, and enough entry space for at least an index entry header.

The shared validator already rejects non-resident records for
resident-only attribute types, including $INDEX_ROOT.

## Which versions are affected by CVE-2026-72199?


## How do I fix CVE-2026-72199?

Apply the vendor's patch.

## Is CVE-2026-72199 being exploited?

There is no known exploitation of CVE-2026-72199 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-72199 and fix it if it is affected.

What it is: CVE-2026-72199 is a critical vulnerability in Linux, published on 15 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-72199 in the wild and no public exploit code.

Affected product: Linux. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-72199/ (Markdown: https://insights.sbomify.com/CVE-2026-72199/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-72199
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-72199
- OSV: https://osv.dev/vulnerability/CVE-2026-72199

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-72199/
Summaries are generated and may contain mistakes; the official description above is the record.