# CVE-2025-38321: smb: Log an error when close_all_cached_dirs fails

> A Linux kernel CIFS bug causes a kernel warning and potential instability during unmount under low memory conditions, requiring a patch to handle allocation failures gracefully.

- **Severity:** High 7.8 (`CVSS:3.1/AV:L/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:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 10 Jul 2025
- **Updated:** 15 Oct 2026
- **Also known as:** AZL-64899, BELL-CVE-2025-38321, DEBIAN-CVE-2025-38321, GHSA-v7vw-mgw4-jqvj, ROOT-OS-DEBIAN-11-CVE-2025-38321, ROOT-OS-DEBIAN-12-CVE-2025-38321, ROOT-OS-UBUNTU-2204-CVE-2025-38321, ROOT-OS-UBUNTU-2404-CVE-2025-38321, UBUNTU-CVE-2025-38321

## What is CVE-2025-38321?

CVE-2025-38321 is a high-severity denial of service vulnerability in Linux kernel, published on 10 Jul 2025. 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: Log an error when close_all_cached_dirs fails

Under low-memory conditions, close_all_cached_dirs() can't move the
dentries to a separate list to dput() them once the locks are dropped.
This will result in a "Dentry still in use" error, so add an error
message that makes it clear this is what happened:

[  495.281119] CIFS: VFS: \\otters.example.com\share Out of memory while dropping dentries
[  495.281595] ------------[ cut here ]------------
[  495.281887] BUG: Dentry ffff888115531138{i=78,n=/}  still in use (2) [unmount of cifs cifs]
[  495.282391] WARNING: CPU: 1 PID: 2329 at fs/dcache.c:1536 umount_check+0xc8/0xf0

Also, bail out of looping through all tcons as soon as a single
allocation fails, since we're already in trouble, and kmalloc() attempts
for subseqeuent tcons are likely to fail just like the first one did.

## Which versions are affected by CVE-2025-38321?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2025-38321?

Apply the vendor's patch.

## Is CVE-2025-38321 being exploited?

There is no known exploitation of CVE-2025-38321 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-2025-38321 and fix it if it is affected.

What it is: CVE-2025-38321 is a high-severity denial of service vulnerability in Linux kernel, published on 10 Jul 2025. 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-2025-38321 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-2025-38321/ (Markdown: https://insights.sbomify.com/CVE-2025-38321/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2025-38321
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2025-38321
- OSV: https://osv.dev/vulnerability/CVE-2025-38321

---
From sbomify Insights: https://insights.sbomify.com/CVE-2025-38321/
Summaries are generated and may contain mistakes; the official description above is the record.