CVE-2026-52911 ksmbd: scope conn->binding slowpath to bound sessions only
An attacker can access unauthorized SMB sessions by exploiting a flaw in the ksmbd connection binding logic, allowing data access or modification.
- 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-2026-52911?
CVE-2026-52911 is a high-severity missing authorization vulnerability in Linux kernel, published on 21 Jun 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: scope conn->binding slowpath to bound sessions only
When the binding SESSION_SETUP sets conn->binding = true, the flag stays set after the call so that the global session lookup in ksmbd_session_lookup_all() can find the session, which was not added to conn->sessions. Because the flag is connection-wide, the global lookup path will also resolve any other session by id if asked.
Tighten the global lookup so that the returned session must have this connection registered in its channel xarray (sess->ksmbd_chann_list). The channel entry is installed by the existing binding_session path in ntlm_authenticate()/krb5_authenticate() when a SESSION_SETUP completes successfully, so this condition is a strict equivalent of "this connection has been accepted as a channel of this session". Connections that have not bound to a given session cannot reach it via the global table.
The existing conn->binding gate for entering the slowpath is preserved so that non-binding connections keep the fast-path-only behavior, and the session->state check is unchanged.
Which versions are affected by CVE-2026-52911?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2026-52911?
Apply the vendor's patch.
Upgrade, and check permissions on every request on the server, not only in the interface. More about Missing authorization.
Is CVE-2026-52911 being exploited?
There is no known exploitation of CVE-2026-52911 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as BELL-CVE-2026-52911, DEBIAN-CVE-2026-52911, GHSA-593m-gq54-r4vq, ROOT-OS-DEBIAN-12-CVE-2026-52911, ROOT-OS-UBUNTU-2204-CVE-2026-52911, ROOT-OS-UBUNTU-2404-CVE-2026-52911 and 1 more.