{
  "schema_version": "1.6.1",
  "id": "RPI-CVE-2026-43376",
  "modified": "2026-10-09T11:39:44Z",
  "upstream": [
    "CVE-2026-43376"
  ],
  "published": "2026-05-08T14:22:57Z",
  "summary": "ksmbd: fix use-after-free by using call_rcu() for oplock_info",
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nksmbd: fix use-after-free by using call_rcu() for oplock_info\n\nksmbd currently frees oplock_info immediately using kfree(), even\nthough it is accessed under RCU read-side critical sections in places\nlike opinfo_get() and proc_show_files().\n\nSince there is no RCU grace period delay between nullifying the pointer\nand freeing the memory, a reader can still access oplock_info\nstructure after it has been freed. This can leads to a use-after-free\nespecially in opinfo_get() where atomic_inc_not_zero() is called on\nalready freed memory.\n\nFix this by switching to deferred freeing using call_rcu().",
  "severity": [
    {
      "type": "CVSS_V3",
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H"
    }
  ],
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  "references": [
    {
      "type": "ADVISORY",
      "url": "https://www.cve.org/CVERecord?id=CVE-2026-43376"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/302fef75512b2c8329a3f5efab1ae7ba2562387a"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/08aa9f3c8cf4d0bee44df540dfe34e8d64069f2c"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/1d6abf145615dbfe267ce3b0a271f95e3780e18e"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/ce8507ee82c888126d8e7565e27c016308d24cde"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/1dfd062caa165ec9d7ee0823087930f3ab8a6294"
    }
  ],
  "database_specific": {
    "source": "https://git.kernel.org/pub/scm/linux/security/vulns.git",
    "upstream_modified": "2026-08-05T13:16:28Z",
    "severity": {
      "source": "kernel CNA",
      "cvss_v3_score": 9.8,
      "cvss_v3_severity": "Critical",
      "scenario": "AV:N - ksmbd is the in-kernel SMB server reachable over TCP/445, and the vulnerable oplock_info lifetime is exercised by remote SMB2 create/close/oplock and lease operations.\nAC:L - The attacker can create oplocks/leases and drive concurrent requests over SMB connections, so the race is attacker-controlled rather than dependent on an external victim condition.\nPR:N - The path is post-session/tree-connect, but ksmbd supports guest/public shares; in the highest reasonable oplocks-enabled guest-share deployment, no prior credentials are needed.\nUI:N - No victim user action is required once the SMB service and share are available; the attacker sends network protocol requests directly.\nS:U - The vulnerable component and impacted resources are the same kernel/host security authority, with no VM, hypervisor, or other scope boundary crossing.\nC:H - This is a kernel heap use-after-free on oplock_info, including stale pointer dereferences after freed memory can be reallocated, which can reasonably enable high-impact kernel information disclosure.\nI:H - The stale atomic_inc_not_zero and later field accesses can corrupt a reallocated kernel object, making arbitrary kernel memory modification or code execution defensible.\nA:H - The UAF can directly trigger kernel memory corruption, oops, panic, or hang, causing high availability impact."
    }
  }
}
