CVE-2026-43379
In the Linux kernel, the following vulnerability has been resolved: ksmbd: fix use-after-free in smb_lazy_parent_lease_break_close() opinfo pointer obtained via rcu_dereference(fp->f_opinfo) is being accessed after rcu_read_unlock() has been called. This creates a race condition where the memory could be freed by a concurrent writer between the unlock and the subsequent pointer dereferences (opinfo->is_lease, etc.), leading to a use-after-free.
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A critical vulnerability has been identified in the Linux kernel SMB server (ksmbd) that could allow remote attackers to execute code with kernel privileges. This use-after-free flaw occurs during the handling of SMB lease breaks and should be patched immediately on any systems utilizing the kernel-mode SMB server.
Severity
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:HEPSS
Technical description
In the Linux kernel, the following vulnerability has been resolved: ksmbd: fix use-after-free in smb_lazy_parent_lease_break_close() opinfo pointer obtained via rcu_dereference(fp->f_opinfo) is being accessed after rcu_read_unlock() has been called. This creates a race condition where the memory could be freed by a concurrent writer between the unlock and the subsequent pointer dereferences (opinfo->is_lease, etc.), leading to a use-after-free.
References
- https://git.kernel.org/stable/c/960699317d39f46611f4ebeb69edc567c1f4e6b6
- https://git.kernel.org/stable/c/b3568347c51c46e2cabc356bc34676df98296619
- https://git.kernel.org/stable/c/bf4d66d72e4a9e268c1012c331ce9eaedb5e2086
- https://git.kernel.org/stable/c/dbbd328cf58261ca239756fe1c0d10c9518d3399
- https://git.kernel.org/stable/c/eac3361e3d5dd8067b3258c69615888eb45e9f25