# CVE-2026-93282: ksmbd: fix maximum allowed access checks

> Flawed access control checks in ksmbd allow unauthorized file access or privilege escalation by mishandling Authenticated Users ACEs and maximal access calculations.

- **Severity:** High 8.1 (`CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 24 Sep 2026
- **Updated:** 21 Oct 2026
- **Also known as:** AZL-103583, BELL-CVE-2026-93282, DEBIAN-CVE-2026-93282, GHSA-7xq8-4f3j-v3g7, UBUNTU-CVE-2026-93282

## What is CVE-2026-93282?

CVE-2026-93282 is a high-severity missing authorization vulnerability in Linux, published on 24 Sep 2026. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

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

ksmbd: fix maximum allowed access checks

The DACL permission check looks for an ACE matching the current user and
falls back to the Everyone ACE. It does not consider an Authenticated
Users ACE, even though an authenticated session is a member of that
well-known group.

As a result, opening a file whose access is granted through S-1-5-11 can
incorrectly fail with STATUS_ACCESS_DENIED. Treat an Authenticated Users
ACE as a fallback entry alongside Everyone.

The maximal access calculation also combines access masks from every ACE,
regardless of whether its SID applies to the current user. This can grant
rights belonging to an unrelated principal. Process only ACEs applying to
the user, Everyone, or Authenticated Users, and accumulate allowed and
denied masks in ACL order. Preserve explicitly requested access bits so
they are validated against the resulting maximal mask.

When ACCESS_SYSTEM_SECURITY is denied, report STATUS_PRIVILEGE_NOT_HELD
instead of the generic STATUS_ACCESS_DENIED. Access to the system ACL
requires a security privilege that ksmbd does not grant.

For regular files, include FILE_EXECUTE in maximal access when the client
requested GENERIC_EXECUTE and the DACL grants the complete file-read set.
Keep a direct FILE_EXECUTE request subject to the explicit DACL bit. This
matches the POSIX file ACL mapping without broadening specific execute
requests.

Do not replace rights from an applicable NT ACE with a POSIX ACL entry.
The POSIX ACL is only a fallback when no user, Everyone, or Authenticated
Users ACE applies; otherwise it can incorrectly broaden the stored DACL.

This fixes smb2.maximum_allowed.maximum_allowed.

## Which versions are affected by CVE-2026-93282?


## How do I fix CVE-2026-93282?

Apply the vendor's patch.

## Is CVE-2026-93282 being exploited?

There is no known exploitation of CVE-2026-93282 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-93282 and fix it if it is affected.

What it is: CVE-2026-93282 is a high-severity missing authorization vulnerability in Linux, published on 24 Sep 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-93282 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-2026-93282/ (Markdown: https://insights.sbomify.com/CVE-2026-93282/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-93282
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-93282
- OSV: https://osv.dev/vulnerability/CVE-2026-93282

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-93282/
Summaries are generated and may contain mistakes; the official description above is the record.