# CVE-2026-72210: ntfs: fix off-by-one in mapping pairs decoding bounds checks

> An off-by-one error in the Linux kernel NTFS driver allows out-of-bounds reads, potentially leading to information disclosure or system crashes.

- **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:** 19 Aug 2026
- **Also known as:** DEBIAN-CVE-2026-72210, GHSA-hpv2-jq93-768m, UBUNTU-CVE-2026-72210

## What is CVE-2026-72210?

CVE-2026-72210 is a critical memory corruption 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: fix off-by-one in mapping pairs decoding bounds checks

In ntfs_mapping_pairs_decompress(), attr_end points one byte past the
end of the attribute record:

    attr_end = (u8 *)attr + le32_to_cpu(attr->length);

The two bounds checks validating that mapping pair data bytes fit within
the attribute use strict greater-than (>), which allows a one-byte
out-of-bounds read when the data extends exactly to attr_end:

  b = *buf & 0xf;
  if (b) {
      if (unlikely(buf + b > attr_end))   // off-by-one
          goto io_error;
      for (deltaxcn = (s8)buf[b--]; b; b--)
          deltaxcn = (deltaxcn << 8) + buf[b];
  }

When buf + b == attr_end, the check evaluates to false and buf[b] reads
one byte past the valid attribute boundary. The same pattern appears in
the LCN delta bytes check.

Fix both checks to use >= so that buf[b] at exactly attr_end is
correctly rejected as out of bounds.

## Which versions are affected by CVE-2026-72210?


## How do I fix CVE-2026-72210?

Apply the vendor's patch.

## Is CVE-2026-72210 being exploited?

There is no known exploitation of CVE-2026-72210 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-72210 and fix it if it is affected.

What it is: CVE-2026-72210 is a critical memory corruption 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-2026-72210 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-2026-72210/ (Markdown: https://insights.sbomify.com/CVE-2026-72210/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-72210
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-72210
- OSV: https://osv.dev/vulnerability/CVE-2026-72210

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-72210/
Summaries are generated and may contain mistakes; the official description above is the record.