# CVE-2026-98318: smb: client: validate absolute native symlink targets before NT fixups

> A user with write access to a mounted SMB share can trigger buffer overflows and integer underflows in the Linux kernel SMB client, potentially leading to code execution or privilege escalation.

- **Severity:** High 7.8 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 6 Oct 2026
- **Updated:** 19 Oct 2026
- **Also known as:** BELL-CVE-2026-98318, DEBIAN-CVE-2026-98318, GHSA-fp2w-r96h-w2cp, UBUNTU-CVE-2026-98318

## What is CVE-2026-98318?

CVE-2026-98318 is a high-severity memory corruption vulnerability in Linux, published on 6 Oct 2026. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

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

smb: client: validate absolute native symlink targets before NT fixups

With symlinkroot unset, an absolute target is copied without conversion
to an NT drive path. Later code still assumes an NT prefix is present
when modifying the target and calculating the print name length.

For "/ab", this causes two failures: sym[5] and path[5] are written
past their allocations, and plen -= 2 * poff subtracts an assumed
8-byte prefix from a 6-byte UTF-16 target, wrapping u16 plen to 65534.
That underflow causes another overflow: memcpy() copies 65534 bytes
into a 24-byte buffer. A user with write access to a mounted share
can trigger these bugs with default settings.

Validate the NT drive prefix, including an ASCII drive letter, before
accessing fixed offsets or subtracting the prefix length.

## Which versions are affected by CVE-2026-98318?


## How do I fix CVE-2026-98318?

Apply the vendor's patch.

## Is CVE-2026-98318 being exploited?

There is no known exploitation of CVE-2026-98318 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-98318 and fix it if it is affected.

What it is: CVE-2026-98318 is a high-severity memory corruption vulnerability in Linux, published on 6 Oct 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-98318 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-2026-98318/ (Markdown: https://insights.sbomify.com/CVE-2026-98318/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-98318
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-98318
- OSV: https://osv.dev/vulnerability/CVE-2026-98318

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-98318/
Summaries are generated and may contain mistakes; the official description above is the record.