# CVE-2026-90162: ksmbd: defer publishing granted locks to prevent UAF/double-free race

> A race condition in the Linux kernel's ksmbd module allows attackers to trigger a use-after-free and double-free, potentially leading to code execution or privilege escalation.

- **Severity:** High 8.8 (`CVSS:3.1/AV:N/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:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 17 Sep 2026
- **Updated:** 21 Oct 2026
- **Also known as:** AZL-102770, BELL-CVE-2026-90162, DEBIAN-CVE-2026-90162, GHSA-x2qc-qfqc-6vmr, UBUNTU-CVE-2026-90162

## What is CVE-2026-90162?

CVE-2026-90162 is a high-severity use after free vulnerability in Linux, published on 17 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: defer publishing granted locks to prevent UAF/double-free race

In smb2_lock(), mid-batch granted locks are published to connection-wide
(conn->lock_list) and file-wide (fp->lock_list) lists immediately upon
vfs_lock_file() success, while also remaining tracked on the stack-local
rollback_list.

If a subsequent element in the same SMB2_LOCK request array fails
validation or execution, the thread jumps to out: and walks
rollback_list to undo previously granted locks. However, because the
granted lock was already published to conn->lock_list, a concurrent
UNLOCK request on the same connection can find the lock object and
kfree() it before the rollback loop executes.

When the granting thread subsequently walks rollback_list, it
dereferences and frees the already-freed ksmbd_lock structure, resulting
in a Use-After-Free and Double-Free (on both ksmbd_lock and struct
file_lock).

Fix this by deferring the publication of granted locks to
conn->lock_list and fp->lock_list until after the entire array of lock
elements has been processed without error. Mid-batch grants remain
tracked exclusively on the request-local rollback_list until the whole
batch succeeds, eliminating the race window.

## Which versions are affected by CVE-2026-90162?


## How do I fix CVE-2026-90162?

Apply the vendor's patch.

## Is CVE-2026-90162 being exploited?

There is no known exploitation of CVE-2026-90162 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-90162 and fix it if it is affected.

What it is: CVE-2026-90162 is a high-severity use after free vulnerability in Linux, published on 17 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-2026-90162 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-2026-90162/ (Markdown: https://insights.sbomify.com/CVE-2026-90162/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-90162
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-90162
- OSV: https://osv.dev/vulnerability/CVE-2026-90162

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-90162/
Summaries are generated and may contain mistakes; the official description above is the record.