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.
- 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
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.
Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.
Is CVE-2025-68219 being exploited?
There is no known exploitation of CVE-2025-68219 in the wild and no public exploit code.
Sources
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 and 2 more.