CVE-2026-52996 (GCVE-0-2026-52996)

Vulnerability from cvelistv5 – Published: 2026-06-24 16:29 – Updated: 2026-06-24 16:29
VLAI
Title
ksmbd: fix durable fd leak on ClientGUID mismatch in durable v2 open
Summary
In the Linux kernel, the following vulnerability has been resolved: ksmbd: fix durable fd leak on ClientGUID mismatch in durable v2 open ksmbd_lookup_fd_cguid() returns a ksmbd_file with its refcount incremented via ksmbd_fp_get(). parse_durable_handle_context() in the DURABLE_REQ_V2 case properly releases this reference on every path inside the ClientGUID-match branch, either by calling ksmbd_put_durable_fd() or by transferring ownership to dh_info->fp for a successful reconnect. However, when an entry exists in the global file table with the same CreateGuid but a different ClientGUID, the code simply falls through to the new-open path without dropping the reference obtained from ksmbd_lookup_fd_cguid(). Per MS-SMB2 section 3.3.5.9.10 ("Handling the SMB2_CREATE_DURABLE_HANDLE_REQUEST_V2 Create Context"), the server MUST locate an Open whose Open.CreateGuid matches the request's CreateGuid AND whose Open.ClientGuid matches the ClientGuid of the connection that received the request. If no such Open is found, the server MUST continue with the normal open execution phase. A CreateGuid hit with a ClientGUID mismatch is therefore the "Open not found" case: proceeding with a new open is correct, but the reference obtained purely as a side effect of the lookup must not be leaked. Repeated requests that hit this mismatch pin global_ft entries, prevent __ksmbd_close_fd() from ever running for the corresponding files, and defeat the durable scavenger, leading to long-lived resource leaks. Release the reference in the mismatch path and clear dh_info->fp so subsequent logic does not mistake a non-matching lookup result for a reconnect target.
Severity
No CVSS data available.
Assigner
References
Impacted products
Vendor Product Version
Linux Linux Affected: 8df4bcdb0a4232192b2445256c39b787d58ef14d , < 407b6e699ba8b45b72cc265eed8a1bc8a7191609 (git)
Affected: c8efcc786146a951091588e5fa7e3c754850cb3c , < f31beef633fbf2b5af7805fa187a10bcff1d4b49 (git)
Affected: c8efcc786146a951091588e5fa7e3c754850cb3c , < 06f709d0e531f3e54d88665dd426be3998a774e6 (git)
Affected: c8efcc786146a951091588e5fa7e3c754850cb3c , < 8c4a0ef19c8264c150833131af34541495832cd0 (git)
Affected: c8efcc786146a951091588e5fa7e3c754850cb3c , < 804054d19886ac6628883d82410f6ee42a818664 (git)
Affected: 6.6.32 , < 6.6.141 (semver)
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Linux Linux Affected: 6.9
Unaffected: 0 , < 6.9 (semver)
Unaffected: 6.6.141 , ≤ 6.6.* (semver)
Unaffected: 6.12.91 , ≤ 6.12.* (semver)
Unaffected: 6.18.33 , ≤ 6.18.* (semver)
Unaffected: 7.0.10 , ≤ 7.0.* (semver)
Unaffected: 7.1 , ≤ * (original_commit_for_fix)
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          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nksmbd: fix durable fd leak on ClientGUID mismatch in durable v2 open\n\nksmbd_lookup_fd_cguid() returns a ksmbd_file with its refcount\nincremented via ksmbd_fp_get(). parse_durable_handle_context() in\nthe DURABLE_REQ_V2 case properly releases this reference on every\npath inside the ClientGUID-match branch, either by calling\nksmbd_put_durable_fd() or by transferring ownership to dh_info-\u003efp\nfor a successful reconnect. However, when an entry exists in the\nglobal file table with the same CreateGuid but a different\nClientGUID, the code simply falls through to the new-open path\nwithout dropping the reference obtained from ksmbd_lookup_fd_cguid().\n\nPer MS-SMB2 section 3.3.5.9.10 (\"Handling the\nSMB2_CREATE_DURABLE_HANDLE_REQUEST_V2 Create Context\"), the server\nMUST locate an Open whose Open.CreateGuid matches the request\u0027s\nCreateGuid AND whose Open.ClientGuid matches the ClientGuid of the\nconnection that received the request. If no such Open is found, the\nserver MUST continue with the normal open execution phase. A\nCreateGuid hit with a ClientGUID mismatch is therefore the\n\"Open not found\" case: proceeding with a new open is correct, but\nthe reference obtained purely as a side effect of the lookup must\nnot be leaked.\n\nRepeated requests that hit this mismatch pin global_ft entries,\nprevent __ksmbd_close_fd() from ever running for the corresponding\nfiles, and defeat the durable scavenger, leading to long-lived\nresource leaks.\n\nRelease the reference in the mismatch path and clear dh_info-\u003efp so\nsubsequent logic does not mistake a non-matching lookup result for\na reconnect target."
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    "dateReserved": "2026-06-09T07:44:35.377Z",
    "dateUpdated": "2026-06-24T16:29:09.113Z",
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  }
}


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Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

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  • Confirmed: The vulnerability has been validated from an analyst's perspective.
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