{"cve":"CVE-2025-40039","nvd":{"published":"2025-10-28T12:15:37.847","modified":"2026-10-19T21:10:00.160","status":"Modified","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nksmbd: Fix race condition in RPC handle list access\n\nThe 'sess->rpc_handle_list' XArray manages RPC handles within a ksmbd\nsession. Access to this list is intended to be protected by\n'sess->rpc_lock' (an rw_semaphore). However, the locking implementation was\nflawed, leading to potential race conditions.\n\nIn ksmbd_session_rpc_open(), the code incorrectly acquired only a read lock\nbefore calling xa_store() and xa_erase(). Since these operations modify\nthe XArray structure, a write lock is required to ensure exclusive access\nand prevent data corruption from concurrent modifications.\n\nFurthermore, ksmbd_session_rpc_method() accessed the list using xa_load()\nwithout holding any lock at all. This could lead to reading inconsistent\ndata or a potential use-after-free if an entry is concurrently removed and\nthe pointer is dereferenced.\n\nFix these issues by:\n1. Using down_write() and up_write() in ksmbd_session_rpc_open()\n   to ensure exclusive access during XArray modification, and ensuring\n   the lock is correctly released on error paths.\n2. Adding down_read() and up_read() in ksmbd_session_rpc_method()\n   to safely protect the lookup.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H","score":4.7},"cwes":["CWE-362"],"references":["https://git.kernel.org/stable/c/305853cce379407090a73b38c5de5ba748893aee","https://git.kernel.org/stable/c/5cc679ba0f4505936124cd4179ba66bb0a4bd9f3","https://git.kernel.org/stable/c/69674b029002b1d90b655f014bdf64f404efa54d","https://git.kernel.org/stable/c/6b615a8fb3af0baf8126cde3d4fee97d57222ffc","https://git.kernel.org/stable/c/6bd7e0e55dcea2cf0d391bbc21c2eb069b4be3e1"],"products":["linux:linux_kernel"],"source":"nvd","synced_at":"2026-10-21T03:43:09.190223697+00:00"},"epss":{"cve":"CVE-2025-40039","score":0.00312,"percentile":0.23917,"date":"2026-10-25"},"kev":null,"osv":[],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}