# CVE-2025-37899: ksmbd: fix use-after-free in session logoff

> A use-after-free in the Linux kernel ksmbd module allows attackers to potentially execute code or escalate privileges via session logoff.

- **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:** 20 May 2025
- **Updated:** 5 Aug 2026
- **Also known as:** BELL-CVE-2025-37899, DEBIAN-CVE-2025-37899, GHSA-3rcg-456g-86p6, ROOT-OS-DEBIAN-12-CVE-2025-37899, ROOT-OS-UBUNTU-2204-CVE-2025-37899, ROOT-OS-UBUNTU-2404-CVE-2025-37899, UBUNTU-CVE-2025-37899

## What is CVE-2025-37899?

CVE-2025-37899 is a high-severity use after free vulnerability in Linux kernel, published on 20 May 2025. 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 use-after-free in session logoff

The sess->user object can currently be in use by another thread, for
example if another connection has sent a session setup request to
bind to the session being free'd. The handler for that connection could
be in the smb2_sess_setup function which makes use of sess->user.

Weakness: CWE-416 (Use After Free)

## Which versions are affected by CVE-2025-37899?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2025-37899?

Apply the vendor's patch.

## Is CVE-2025-37899 being exploited?

There is no known exploitation of CVE-2025-37899 in the wild and no public exploit code.

Public exploit code:

- Artefacts for blog post on finding CVE-2025-37899 with o3 (github_poc): https://github.com/SeanHeelan/o3_finds_cve-2025-37899
- https://github.com/vett3x/SMB-LINUX-CVE-2025-37899 (github_poc): https://github.com/vett3x/SMB-LINUX-CVE-2025-37899
- Artefacts for blog post on finding CVE-2025-37899 with o3 (github_poc): https://github.com/ccss17/o3_finds_cve-2025-37899

## 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-2025-37899 and fix it if it is affected.

What it is: CVE-2025-37899 is a high-severity use after free vulnerability in Linux kernel, published on 20 May 2025. Any signed-in user can exploit it over the network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2025-37899 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-2025-37899/ (Markdown: https://insights.sbomify.com/CVE-2025-37899/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2025-37899
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2025-37899
- OSV: https://osv.dev/vulnerability/CVE-2025-37899

---
From sbomify Insights: https://insights.sbomify.com/CVE-2025-37899/
Summaries are generated and may contain mistakes; the official description above is the record.