# CVE-2026-72318: cifs: validate DFS referral string offsets

> A malformed DFS referral in the Linux kernel CIFS module can cause out-of-bounds reads, potentially leading to denial of service or information disclosure.

- **Severity:** Critical 9.4 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/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:** 16 Oct 2026
- **Also known as:** BELL-CVE-2026-72318, DEBIAN-CVE-2026-72318, GHSA-4cv4-fc78-7hch, UBUNTU-CVE-2026-72318

## What is CVE-2026-72318?

CVE-2026-72318 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:

cifs: validate DFS referral string offsets

parse_dfs_referrals() validates that the response header and referral
array fit in the received buffer, but each referral also contains string
offsets supplied by the server.

Those offsets are used to compute the DfsPath and NetworkAddress string
pointers without checking whether they still point inside the response
buffer. A malformed referral can therefore make the computed pointer
exceed the end of the buffer. The resulting negative max_len is then
passed to cifs_strndup_from_utf16(), and the non-Unicode path forwards it
to kstrndup() as a size_t, allowing strnlen() to read out of bounds.

Validate each string offset before deriving the string pointer.

## Which versions are affected by CVE-2026-72318?


## How do I fix CVE-2026-72318?

Apply the vendor's patch.

## Is CVE-2026-72318 being exploited?

There is no known exploitation of CVE-2026-72318 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-72318 and fix it if it is affected.

What it is: CVE-2026-72318 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-2026-72318 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-2026-72318/ (Markdown: https://insights.sbomify.com/CVE-2026-72318/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-72318
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-72318
- OSV: https://osv.dev/vulnerability/CVE-2026-72318

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-72318/
Summaries are generated and may contain mistakes; the official description above is the record.