# CVE-2026-43376: ksmbd: fix use-after-free by using call_rcu() for oplock_info

> A use-after-free vulnerability in the Linux kernel's ksmbd module allows attackers to execute arbitrary code or escalate privileges via improper memory handling.

- **Severity:** Critical 9.8 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/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:** 8 May 2026
- **Updated:** 5 Aug 2026
- **Also known as:** BELL-CVE-2026-43376, DEBIAN-CVE-2026-43376, GHSA-3v8x-c22j-hv4q, UBUNTU-CVE-2026-43376

## What is CVE-2026-43376?

CVE-2026-43376 is a critical use after free vulnerability in Linux kernel, published on 8 May 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: fix use-after-free by using call_rcu() for oplock_info

ksmbd currently frees oplock_info immediately using kfree(), even
though it is accessed under RCU read-side critical sections in places
like opinfo_get() and proc_show_files().

Since there is no RCU grace period delay between nullifying the pointer
and freeing the memory, a reader can still access oplock_info
structure after it has been freed. This can leads to a use-after-free
especially in opinfo_get() where atomic_inc_not_zero() is called on
already freed memory.

Fix this by switching to deferred freeing using call_rcu().

Weakness: CWE-416 (Use After Free)

## Which versions are affected by CVE-2026-43376?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2026-43376?

Apply the vendor's patch.

## Is CVE-2026-43376 being exploited?

There is no known exploitation of CVE-2026-43376 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-2026-43376 and fix it if it is affected.

What it is: CVE-2026-43376 is a critical use after free vulnerability in Linux kernel, published on 8 May 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-2026-43376 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-2026-43376/ (Markdown: https://insights.sbomify.com/CVE-2026-43376/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-43376
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-43376
- OSV: https://osv.dev/vulnerability/CVE-2026-43376

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-43376/
Summaries are generated and may contain mistakes; the official description above is the record.