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.
SSVC (CISA's decision table, applied by EchelonGraph)Track at low or medium mission impact; Track* at high (mission-essential systems).
A fix is available. Apply it within your standard update timelines.
Exploitation none (no CISA value, KEV listing or exploit code on record) · Automatable no (CISA's BOD 26-04 default) · Technical impact total (CISA's BOD 26-04 default). EchelonGraph holds no SSVC assessment of this CVE from CISA: none of these inputs is from Vulnrichment. EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE. Mission impact is CISA's Mission & Well-being decision point, and only you can judge it. CISA's table makes it high when Mission Prevalence is Essential — the vulnerable component "directly provides capabilities that constitute at least one MEF for at least one entity" (MEF: mission essential function) — or when Public Well-Being Impact is Irreversible: "multiple fatalities are likely", the cyber-physical system "is likely lost or destroyed", "extreme or serious externalities" are imposed on other parties, or social systems such as elections or the financial grid "are destabilized and potentially collapse". CISA's decision table
BOD 26-04 (CISA's remediation timeline, Table 1)14 days if the affected system is publicly exposed; Fix on system upgrade if it is not.
In CISA KEV no (CISA's KEV catalog) · Automatable no (CISA's BOD 26-04 default) · Technical impact total (CISA's BOD 26-04 default). Where an input reads “CISA's BOD 26-04 default”, no one has published it for this CVE, and CISA's implementation guidance says: “If “Automatable” and “Technical Impact” information items about a CVE ID are not available and the CVE ID is not in the KEV Catalog, CISA will treat its values as “no” and “total,” respectively, until CISA or a third party provides metadata about the CVE ID. CISA will always provide the Vulnrichment data for a CVE ID listed in the KEV Catalog.” Whether your system is publicly exposed is yours to answer. BOD 26-04 binds US Federal Civilian Executive Branch agencies; for anyone else it is CISA's published timeline, a reference rather than an obligation. The directive · how EchelonGraph applies it