CVE-2026-93811 ksmbd: Fix acl.sd_buf memory leak and invalid sd_size error handling

Q: Is CVE-2026-93811 being exploited?

There is no known exploitation of CVE-2026-93811 in the wild and no public exploit code.

Not scored Published 24 Sep 2026 Updated 3 Oct 2026

A memory leak and improper error handling in the Linux kernel ksmbd module can lead to resource exhaustion and denial of service.

Exploited in the wild: Not known
Login needed: Any signed-in user
Attackable: Over the internet
Victim action needed: Not needed
Fix: Available

What is CVE-2026-93811?

CVE-2026-93811 is a memory corruption vulnerability in Linux, published on 24 Sep 2026. 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 acl.sd_buf memory leak and invalid sd_size error handling

1. When ndr_decode_v4_ntacl() fails, the code jumped to free_n_data which only freed n.data, skipping kfree(acl.sd_buf) and leaking the buffer. Zero-initialize struct xattr_ntacl acl, reorder error labels to out_free to release acl.sd_buf on all error paths.

2. if (acl.sd_size < sizeof(struct smb_ntsd)) is true, original code returned success without freeing sd_buf and left stale *pntsd. Set rc = -EINVAL before jumping to out_free to return error code and free buffer.

Which versions are affected by CVE-2026-93811?

How do I fix CVE-2026-93811?

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-2026-93811 being exploited?