# CVE-2025-68219: cifs: fix memory leak in smb3_fs_context_parse_param error path

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

- **Severity:** Not scored
- **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:** 16 Dec 2025
- **Updated:** 11 May 2026
- **Also known as:** AZL-72463, BELL-CVE-2025-68219, DEBIAN-CVE-2025-68219, GHSA-6qvg-p925-pxr9, ROOT-OS-DEBIAN-12-CVE-2025-68219, ROOT-OS-UBUNTU-2204-CVE-2025-68219, ROOT-OS-UBUNTU-2404-CVE-2025-68219, UBUNTU-CVE-2025-68219

## What is CVE-2025-68219?

CVE-2025-68219 is a memory corruption vulnerability in Linux, published on 16 Dec 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:

cifs: fix memory leak in smb3_fs_context_parse_param error path

Add proper cleanup of ctx->source and fc->source to the
cifs_parse_mount_err error handler. This ensures that memory allocated
for the source strings is correctly freed on all error paths, matching
the cleanup already performed in the success path by
smb3_cleanup_fs_context_contents().
Pointers are also set to NULL after freeing to prevent potential
double-free issues.

This change fixes a memory leak originally detected by syzbot. The
leak occurred when processing Opt_source mount options if an error
happened after ctx->source and fc->source were successfully
allocated but before the function completed.

The specific leak sequence was:
1. ctx->source = smb3_fs_context_fullpath(ctx, '/') allocates memory
2. fc->source = kstrdup(ctx->source, GFP_KERNEL) allocates more memory
3. A subsequent error jumps to cifs_parse_mount_err
4. The old error handler freed passwords but not the source strings,
causing the memory to leak.

This issue was not addressed by commit e8c73eb7db0a ("cifs: client:
fix memory leak in smb3_fs_context_parse_param"), which only fixed
leaks from repeated fsconfig() calls but not this error path.

Patch updated with minor change suggested by kernel test robot

## Which versions are affected by CVE-2025-68219?


## How do I fix CVE-2025-68219?

Apply the vendor's patch.

## Is CVE-2025-68219 being exploited?

There is no known exploitation of CVE-2025-68219 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2025-68219 and fix it if it is affected.

What it is: CVE-2025-68219 is a memory corruption vulnerability in Linux, published on 16 Dec 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-2025-68219 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-2025-68219/ (Markdown: https://insights.sbomify.com/CVE-2025-68219/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2025-68219
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2025-68219
- OSV: https://osv.dev/vulnerability/CVE-2025-68219

---
From sbomify Insights: https://insights.sbomify.com/CVE-2025-68219/
Summaries are generated and may contain mistakes; the official description above is the record.