# CVE-2026-68457: ksmbd: use opener credentials for FSCTL mutations

> Attackers can bypass permission checks on SMB file operations by exploiting credential mishandling in the ksmbd kernel module.

- **Severity:** Critical 9.1 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/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:** BELL-CVE-2026-68457, DEBIAN-CVE-2026-68457, GHSA-j57w-wqmx-67hp, UBUNTU-CVE-2026-68457

## What is CVE-2026-68457?

CVE-2026-68457 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:

ksmbd: use opener credentials for FSCTL mutations

SET_SPARSE, SET_ZERO_DATA and SET_COMPRESSION operate on an open SMB
handle but call VFS xattr, fallocate or fileattr helpers with the current
ksmbd worker credentials. Those helpers can revalidate inode permissions,
ownership and LSM policy independently of the SMB handle access mask.

Run each operation with the credentials captured in the target file when
the handle was opened. Keep credential handling local to these single-file
FSCTLs rather than applying session credentials to the complete IOCTL
handler, which also contains handle-less and multi-handle operations.

## Which versions are affected by CVE-2026-68457?


## How do I fix CVE-2026-68457?

Apply the vendor's patch.

## Is CVE-2026-68457 being exploited?

There is no known exploitation of CVE-2026-68457 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-68457 and fix it if it is affected.

What it is: CVE-2026-68457 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-2026-68457 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-2026-68457/ (Markdown: https://insights.sbomify.com/CVE-2026-68457/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-68457
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-68457
- OSV: https://osv.dev/vulnerability/CVE-2026-68457

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-68457/
Summaries are generated and may contain mistakes; the official description above is the record.