CVE-2023-54250 ksmbd: avoid out of bounds access in decode_preauth_ctxt()
An out-of-bounds access in the Linux kernel's ksmbd module allows attackers to cause denial of service or potentially execute code via crafted SMB requests.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2023-54250?
CVE-2023-54250 is a high-severity memory corruption vulnerability in Linux, published on 30 Dec 2025. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
In the Linux kernel, the following vulnerability has been resolved:
ksmbd: avoid out of bounds access in decode_preauth_ctxt()
Confirm that the accessed pneg_ctxt->HashAlgorithms address sits within the SMB request boundary; deassemble_neg_contexts() only checks that the eight byte smb2_neg_context header + (client controlled) DataLength are within the packet boundary, which is insufficient.
Checking for sizeof(struct smb2_preauth_neg_context) is overkill given that the type currently assumes SMB311_SALT_SIZE bytes of trailing Salt.
Which versions are affected by CVE-2023-54250?
How do I fix CVE-2023-54250?
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-2023-54250 being exploited?
There is no known exploitation of CVE-2023-54250 in the wild and no public exploit code.
Sources
Also known as BELL-CVE-2023-54250, DEBIAN-CVE-2023-54250, GHSA-f39w-x49r-j8p2, UBUNTU-CVE-2023-54250.