CVE-2026-68130 ksmbd: defer destroy_previous_session() until after NTLM authentication
An authenticated attacker can terminate a victim's SMB session by manipulating NTLM authentication fields, causing a 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-2026-68130?
CVE-2026-68130 is a denial of service vulnerability in Linux, published on 10 Aug 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: defer destroy_previous_session() until after NTLM authentication
In ntlm_authenticate(), destroy_previous_session() is called using a user pointer resolved from the client-supplied NTLM blob username field before the NTLMv2 response is validated. An authenticated attacker can set the NTLM blob username to match a victim account and set PreviousSessionId to the victim's session ID; destroy_previous_session() destroys the victim's session while ksmbd_decode_ntlmssp_auth_blob() subsequently rejects the request with -EPERM.
Move destroy_previous_session() and the prev_id assignment to after ksmbd_decode_ntlmssp_auth_blob() returns success and use sess->user rather than the pre-authentication lookup result. This matches the ordering already used by krb5_authenticate(), where destroy_previous_session() is called only after ksmbd_krb5_authenticate() returns success.
Which versions are affected by CVE-2026-68130?
How do I fix CVE-2026-68130?
Apply the vendor's patch.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2026-68130 being exploited?
There is no known exploitation of CVE-2026-68130 in the wild and no public exploit code.
Sources
Also known as BELL-CVE-2026-68130, DEBIAN-CVE-2026-68130, GHSA-cjmw-xwhw-8r5x, UBUNTU-CVE-2026-68130.