{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2025-40039", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2025-04-16T07:20:57.153Z", "datePublished": "2025-10-28T11:48:19.781Z", "dateUpdated": "2026-08-05T12:07:13.052Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-05T12:07:13.052Z" }, "descriptions": [ { "lang": "en", "value": "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." } ], "metrics": [ { "cvssV3_1": { "version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H", "baseScore": 8.8, "baseSeverity": "HIGH" }, "scenarios": [ { "lang": "en", "value": "AV:N - The vulnerable code is in ksmbd, the in-kernel SMB server, and is driven entirely by SMB2 requests (CREATE/CLOSE/IOCTL/READ/WRITE/QUERY_INFO) arriving over TCP port 445 from a remote peer. No local access is needed.\nAC:L - The attacker controls both sides of the race: the pipe handle is an attacker-chosen VolatileFileId, and ksmbd_queue_work() executes each SMB2 request on a separate ksmbd-io worker (plus SMB3 multichannel), so concurrent SMB2_CLOSE and SMB2_IOCTL/READ/WRITE requests run in parallel with unlimited retries.\nPR:L - Reaching create_smb2_pipe() requires a session in SMB2_SESSION_VALID state (ksmbd_session_lookup_all() rejects IN_PROGRESS) plus a tree connect to IPC$, i.e. any valid low-privileged SMB account; no administrative rights are needed, and with guest mapping enabled even credentials are unnecessary.\nUI:N - The entire sequence is performed by the attacker's own SMB client against the server; no action by any local user or administrator is required.\nS:U - The use-after-free corrupts kernel heap state within the same kernel security authority; no hypervisor, IOMMU, or sandbox boundary is crossed.\nC:H - The unlocked xa_load() dereferences a kfree()'d struct ksmbd_session_rpc, disclosing reused kernel heap contents as the RPC method flags; a UAF of this kind gives control over freed-object contents and can be leveraged into arbitrary kernel memory disclosure, and the resulting flags can steer the root ksmbd.mountd daemon into SAMR/LSARPC handlers the client never opened.\nI:H - The stale entry->method value read from a reused 8-byte slab object is heap-groomable by the attacker and directly selects which privileged RPC method the root-privileged userspace daemon executes with client-supplied payload; use-after-free conditions are generally leverageable into arbitrary-write and control-flow hijack primitives.\nA:H - Dereferencing the freed entry after the slab object or page has been released oopses the ksmbd worker thread, and the unsynchronized RPC handle teardown corrupts session state, yielding a repeatable remote kernel crash / denial of service." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "fs/smb/server/mgmt/user_session.c" ], "versions": [ { "version": "a4348710a7267705b75692dc1a000920481d1d92", "lessThan": "69674b029002b1d90b655f014bdf64f404efa54d", "status": "affected", "versionType": "git" }, { "version": "b685757c7b08d5073046fb379be965fd6c06aafc", "lessThan": "6b615a8fb3af0baf8126cde3d4fee97d57222ffc", "status": "affected", "versionType": "git" }, { "version": "b685757c7b08d5073046fb379be965fd6c06aafc", "lessThan": "5cc679ba0f4505936124cd4179ba66bb0a4bd9f3", "status": "affected", "versionType": "git" }, { "version": "b685757c7b08d5073046fb379be965fd6c06aafc", "lessThan": "6bd7e0e55dcea2cf0d391bbc21c2eb069b4be3e1", "status": "affected", "versionType": "git" }, { "version": "b685757c7b08d5073046fb379be965fd6c06aafc", "lessThan": "305853cce379407090a73b38c5de5ba748893aee", "status": "affected", "versionType": "git" }, { "version": "1f485b54d04a920723984062c912174330a05178", "status": "affected", "versionType": "git" }, { "version": "052b41ef2abe274f068e892aee81406f11bd1f3a", "status": "affected", "versionType": "git" }, { "version": "5.15.145", "lessThan": "5.16", "status": "affected", "versionType": "semver" } ] }, { "product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "fs/smb/server/mgmt/user_session.c" ], "versions": [ { "version": "6.3", "status": "affected" }, { "version": "0", "lessThan": "6.3", "status": "unaffected", "versionType": "semver" }, { "version": "6.6.123", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.12.53", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.17.3", "lessThanOrEqual": "6.17.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.18", "lessThanOrEqual": "*", "status": "unaffected", "versionType": "original_commit_for_fix" } ] } ], "cpeApplicability": [ { "nodes": [ { "operator": "OR", "negate": false, "cpeMatch": [ { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.3", "versionEndExcluding": "6.6.123" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.3", "versionEndExcluding": "6.12.53" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.3", "versionEndExcluding": "6.17.3" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.3", "versionEndExcluding": "6.18" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.15.145" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/69674b029002b1d90b655f014bdf64f404efa54d" }, { "url": "https://git.kernel.org/stable/c/6b615a8fb3af0baf8126cde3d4fee97d57222ffc" }, { "url": "https://git.kernel.org/stable/c/5cc679ba0f4505936124cd4179ba66bb0a4bd9f3" }, { "url": "https://git.kernel.org/stable/c/6bd7e0e55dcea2cf0d391bbc21c2eb069b4be3e1" }, { "url": "https://git.kernel.org/stable/c/305853cce379407090a73b38c5de5ba748893aee" } ], "title": "ksmbd: Fix race condition in RPC handle list access", "x_generator": { "engine": "bippy-1.2.0" } } } }