# CVE-2026-64379: smb: client: mask server-provided mode to 07777 in modefromsid

> A missing mask in the Linux kernel SMB client allows a malicious server to set arbitrary file permissions, potentially leading to privilege escalation.

- **Severity:** High 7.1 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** A user has to click or open something
- **Fix available:** Yes
- **Published:** 25 Jul 2026
- **Updated:** 19 Oct 2026
- **Also known as:** AZL-93647, BELL-CVE-2026-64379, DEBIAN-CVE-2026-64379, GHSA-fhph-rcwp-75hp, ROOT-OS-DEBIAN-12-CVE-2026-64379, ROOT-OS-UBUNTU-2204-CVE-2026-64379, UBUNTU-CVE-2026-64379

## What is CVE-2026-64379?

CVE-2026-64379 is a high-severity vulnerability in Linux kernel, published on 25 Jul 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.

### Official description

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

smb: client: mask server-provided mode to 07777 in modefromsid

When modefromsid is active, parse_dacl() applies the server-provided
sub_auth[2] value from the NFS mode SID to cf_mode without masking to
07777. Apply the correct masking, same as in the read path.

Weakness: CWE-20 (Improper Input Validation)

## Which versions are affected by CVE-2026-64379?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2026-64379?

Apply the vendor's patch.

## Is CVE-2026-64379 being exploited?

There is no known exploitation of CVE-2026-64379 in the wild and no public exploit code.

## Other vulnerabilities in Linux kernel

- [CVE-2026-53266](https://insights.sbomify.com/CVE-2026-53266/): Linux Kernel Out-of-Bounds Write (high 8.8, exploited in the wild)
- [CVE-2013-6282](https://insights.sbomify.com/CVE-2013-6282/): Linux Kernel Improper Input Validation (high 8.8, exploited in the wild)
- [CVE-2022-0185](https://insights.sbomify.com/CVE-2022-0185/): Linux Kernel Heap-Based Buffer Overflow (high 8.4, exploited in the wild)
- [CVE-2013-2094](https://insights.sbomify.com/CVE-2013-2094/): Linux Kernel Privilege Escalation (high 8.4, exploited in the wild)
- [CVE-2026-53362](https://insights.sbomify.com/CVE-2026-53362/): Linux Kernel Unspecified (high 7.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-64379 and fix it if it is affected.

What it is: CVE-2026-64379 is a high-severity vulnerability in Linux kernel, published on 25 Jul 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Exploitation: There is no known exploitation of CVE-2026-64379 in the wild and no public exploit code.

Affected product: Linux kernel. 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-2026-64379/ (Markdown: https://insights.sbomify.com/CVE-2026-64379/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-64379
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-64379
- OSV: https://osv.dev/vulnerability/CVE-2026-64379

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-64379/
Summaries are generated and may contain mistakes; the official description above is the record.