CVE-2025-38437 (GCVE-0-2025-38437)
Vulnerability from cvelistv5
Published
2025-07-25 15:27
Modified
2026-08-05 12:01
Severity ?
8.8 (High) - CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Summary
In the Linux kernel, the following vulnerability has been resolved: ksmbd: fix potential use-after-free in oplock/lease break ack If ksmbd_iov_pin_rsp return error, use-after-free can happen by accessing opinfo->state and opinfo_put and ksmbd_fd_put could called twice.
References
Impacted products
Vendor Product Version
Linux Linux Version: 0626e6641f6b467447c81dd7678a69c66f7746cf
Version: 0626e6641f6b467447c81dd7678a69c66f7746cf
Version: 0626e6641f6b467447c81dd7678a69c66f7746cf
Version: 0626e6641f6b467447c81dd7678a69c66f7746cf
Version: 0626e6641f6b467447c81dd7678a69c66f7746cf
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          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nksmbd: fix potential use-after-free in oplock/lease break ack\n\nIf ksmbd_iov_pin_rsp return error, use-after-free can happen by\naccessing opinfo-\u003estate and opinfo_put and ksmbd_fd_put could\ncalled twice."
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              "value": "AV:N - The vulnerable code is the ksmbd in-kernel SMB server\u0027s SMB2_OPLOCK_BREAK handler (fs/smb/server/smb2pdu.c), reached directly from an SMB2 PDU received on TCP/445. No local access is required.\nAC:L - The attacker fully controls both sides of the sequence \u2014 granting the oplock/lease, triggering the break from a second connection, and sending the ack \u2014 and can drive the only remaining condition (a `krealloc` failure under `__GFP_RETRY_MAYFAIL`, which fails instead of OOM-killing) by compounding many acks to force repeated iov growth while exhausting kernel memory with concurrent connections and large buffers.\nPR:L - `smb2_check_user_session()` rejects SMB2_OPLOCK_BREAK without a valid session, and the path needs a tree connect plus an open handle holding an oplock or lease, so a basic authenticated share user (or a guest account where the share permits it) is required.\nUI:N - The attacker performs every step \u2014 file open, conflicting open to force the break, and the oplock/lease break ack \u2014 with no action by any legitimate user or administrator.\nS:U - The corruption and its impact are confined to the kernel\u0027s own memory and the ksmbd server\u0027s security authority; no VM, IOMMU, or sandbox boundary is crossed.\nC:H - The refcount underflow frees a still-linked `struct oplock_info` and an extra reference on `struct ksmbd_conn`/`struct ksmbd_file`, so subsequent dereferences of `opinfo-\u003econn`, `-\u003esess`, `-\u003eo_fp` and the waitqueue lists read heap the attacker can groom, yielding kernel memory disclosure.\nI:H - The freed object contains two list_heads and two wait_queue_heads still referenced by `fp-\u003ef_opinfo`, `ci-\u003em_op_list` and the lease table; reallocating it lets `wake_up_interruptible_all()` invoke an attacker-supplied `wait_queue_entry-\u003efunc` pointer and lets list unlink act as a write-what-where, giving arbitrary write and code execution.\nA:H - Even without successful exploitation the use-after-free, refcount underflow, and premature `__ksmbd_close_fd()`/connection release reliably produce oops or panic, and the attack can be repeated to keep the server down."
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        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
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          "url": "https://git.kernel.org/stable/c/50f930db22365738d9387c974416f38a06e8057e"
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    "cveId": "CVE-2025-38437",
    "datePublished": "2025-07-25T15:27:16.995Z",
    "dateReserved": "2025-04-16T04:51:24.016Z",
    "dateUpdated": "2026-08-05T12:01:53.911Z",
    "state": "PUBLISHED"
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