Critical severity · published Sep 11, 2026
CVE-2026-80926
ksmbd: fix use-after-free in oplock break notification
9.8
CVSS
0.4%
EPSS
No
On KEV
Description
In the Linux kernel, the following vulnerability has been resolved:
ksmbd: fix use-after-free in oplock break notification
smb2_oplock_break_noti() reads opinfo->conn without any lock and
dereferences it after two allocations which may sleep. When the
durable handle owning the oplock is disconnected, session_fd_check()
clears opinfo->conn and drops its conn reference under ci->m_lock, and
the last ksmbd_conn_put() frees the connection. A break triggered by
another connection that races with the teardown can then resurrect the
freed connection: ksmbd_conn_get() is a plain atomic_inc, and the
queued break work later dereferences the stale conn via
ksmbd_conn_write(), a use-after-free reachable by any authenticated
client holding a durable batch oplock.
Thread the caller's inode into the notification path instead of taking
a new reference on it. Every caller of oplock_break() already holds a
live ksmbd_file (or an explicit ksmbd_inode_lookup_lock() reference,
in the parent lease break paths) on the inode that owns the break
target's oplock list, so ci cannot be freed during the call, and its
lock can be taken without dereferencing opinfo->o_fp, which a
concurrent close may free. Select and pin the connection under
ci->m_lock, the same lock session_fd_check() and
ksmbd_reopen_durable_fd() use to update opinfo->conn, so a concurrent
detach either loses the race to the clear or keeps the connection
alive until the notification work releases it. Transfer the reference
to the work item and release it on allocation failures.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Confidentiality
High
Integrity
High
Availability
High
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.4% · higher than 38% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
LI
Linux · Linux
945a86b21b40fb17183f5b27461baa6f03e2467f before 892f643b141aee3f7aa7c0fc61ddcb55c59f1996; 1ff58dcfcab434ebb51649da33774fbb8e1f7b67 before 5de0527f782430b1109a447646e32033ad018a6a; e735dbd489e3ea02be78dba991056fe1138be51e before c8279ae8df68cce9cd3b785e85f7a86c80a46e78; b003086d76968298f22e7cf62239833b5a3a06b1 before 8cc98db4fc590e6c7d9db6529320982ee16c5d1d; b003086d76968298f22e7cf62239833b5a3a06b1 before 0e753899627b5e28a9fea8bca98262a6f65a2452; 75e33deda658c1ab3a9336cbdb1436536f9b3660; +5 more · source: vendor
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-80926
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-80926
git.kernel.org
https://git.kernel.org/stable/c/892f643b141aee3f7aa7c0fc61ddcb55c59f1996
git.kernel.org
https://git.kernel.org/stable/c/5de0527f782430b1109a447646e32033ad018a6a
git.kernel.org
https://git.kernel.org/stable/c/c8279ae8df68cce9cd3b785e85f7a86c80a46e78
git.kernel.org
https://git.kernel.org/stable/c/8cc98db4fc590e6c7d9db6529320982ee16c5d1d
git.kernel.org
https://git.kernel.org/stable/c/0e753899627b5e28a9fea8bca98262a6f65a2452
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