Bug 2516669 (CVE-2026-72492)

Summary: CVE-2026-72492 kernel: ksmbd: fix use-after-free in same_client_has_lease()
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
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Priority: medium    
Version: unspecifiedCC: rhel-process-autobot, watson-tool-maintainers
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Hardware: All   
OS: Linux   
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A flaw was found in ksmbd, the in-kernel SMB3 server for Linux. This memory corruption vulnerability, known as a use-after-free, occurs when the system attempts to use memory after it has been released. A remote attacker could trigger this by performing a concurrent close operation during lease handling, leading to system instability, information disclosure, or potentially arbitrary code execution.
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Description OSIDB Bzimport 2026-08-15 06:24:59 UTC 
In the Linux kernel, the following vulnerability has been resolved:

ksmbd: fix use-after-free in same_client_has_lease()

same_client_has_lease() returns an opinfo pointer from ci->m_op_list
after dropping ci->m_lock without taking a reference.

smb_grant_oplock() then dereferences that pointer in copy_lease() and
when checking breaking_cnt. A concurrent close can remove the old lease
from ci->m_op_list and drop the last reference before the caller uses
the returned pointer, leading to a use-after-free.

Take a reference when same_client_has_lease() selects an existing lease,
drop any previous match while scanning, and release the returned
reference in smb_grant_oplock() after copying the lease state.
Comment 1 gkamathe 2026-08-19 06:53:04 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2026081539-CVE-2026-72492-b49b@gregkh/T