# CVE-2026-23205: smb/client: fix memory leak in smb2_open_file()

> A memory leak in the Linux kernel CIFS client allows local attackers to exhaust kernel memory, potentially causing a denial of service.

- **Severity:** Medium 5.5 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 14 Feb 2026
- **Updated:** 23 May 2026
- **Also known as:** BELL-CVE-2026-23205, DEBIAN-CVE-2026-23205, GHSA-9rcv-5g2j-597r, ROOT-OS-DEBIAN-12-CVE-2026-23205, ROOT-OS-DEBIAN-13-CVE-2026-23205, ROOT-OS-UBUNTU-2404-CVE-2026-23205, UBUNTU-CVE-2026-23205

## What is CVE-2026-23205?

CVE-2026-23205 is a medium-severity denial of service vulnerability in Linux kernel, published on 14 Feb 2026. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

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

smb/client: fix memory leak in smb2_open_file()

Reproducer:

  1. server: directories are exported read-only
  2. client: mount -t cifs //${server_ip}/export /mnt
  3. client: dd if=/dev/zero of=/mnt/file bs=512 count=1000 oflag=direct
  4. client: umount /mnt
  5. client: sleep 1
  6. client: modprobe -r cifs

The error message is as follows:

  =============================================================================
  BUG cifs_small_rq (Not tainted): Objects remaining on __kmem_cache_shutdown()
  -----------------------------------------------------------------------------

  Object 0x00000000d47521be @offset=14336
  ...
  WARNING: mm/slub.c:1251 at __kmem_cache_shutdown+0x34e/0x440, CPU#0: modprobe/1577
  ...
  Call Trace:
   <TASK>
   kmem_cache_destroy+0x94/0x190
   cifs_destroy_request_bufs+0x3e/0x50 [cifs]
   cleanup_module+0x4e/0x540 [cifs]
   __se_sys_delete_module+0x278/0x400
   __x64_sys_delete_module+0x5f/0x70
   x64_sys_call+0x2299/0x2ff0
   do_syscall_64+0x89/0x350
   entry_SYSCALL_64_after_hwframe+0x76/0x7e
  ...
  kmem_cache_destroy cifs_small_rq: Slab cache still has objects when called from cifs_destroy_request_bufs+0x3e/0x50 [cifs]
  WARNING: mm/slab_common.c:532 at kmem_cache_destroy+0x16b/0x190, CPU#0: modprobe/1577

Weakness: CWE-401 (Missing Release of Memory after Effective Lifetime)

## Which versions are affected by CVE-2026-23205?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2026-23205?

Apply the vendor's patch.

## Is CVE-2026-23205 being exploited?

There is no known exploitation of CVE-2026-23205 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-2026-23205 and fix it if it is affected.

What it is: CVE-2026-23205 is a medium-severity denial of service vulnerability in Linux kernel, published on 14 Feb 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-23205 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-2026-23205/ (Markdown: https://insights.sbomify.com/CVE-2026-23205/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-23205
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-23205
- OSV: https://osv.dev/vulnerability/CVE-2026-23205

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-23205/
Summaries are generated and may contain mistakes; the official description above is the record.