{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2023-54203", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2025-12-30T12:06:44.499Z", "datePublished": "2025-12-30T12:09:07.538Z", "dateUpdated": "2026-08-05T09:18:01.954Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-05T09:18:01.954Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nksmbd: fix slab-out-of-bounds in init_smb2_rsp_hdr\n\nWhen smb1 mount fails, KASAN detect slab-out-of-bounds in\ninit_smb2_rsp_hdr like the following one.\nFor smb1 negotiate(56bytes) , init_smb2_rsp_hdr() for smb2 is called.\nThe issue occurs while handling smb1 negotiate as smb2 server operations.\nAdd smb server operations for smb1 (get_cmd_val, init_rsp_hdr,\nallocate_rsp_buf, check_user_session) to handle smb1 negotiate so that\nsmb2 server operation does not handle it.\n\n[ 411.400423] CIFS: VFS: Use of the less secure dialect vers=1.0 is\nnot recommended unless required for access to very old servers\n[ 411.400452] CIFS: Attempting to mount \\\\192.168.45.139\\homes\n[ 411.479312] ksmbd: init_smb2_rsp_hdr : 492\n[ 411.479323] ==================================================================\n[ 411.479327] BUG: KASAN: slab-out-of-bounds in\ninit_smb2_rsp_hdr+0x1e2/0x1f4 [ksmbd]\n[ 411.479369] Read of size 16 at addr ffff888488ed0734 by task kworker/14:1/199\n\n[ 411.479379] CPU: 14 PID: 199 Comm: kworker/14:1 Tainted: G\n OE 6.1.21 #3\n[ 411.479386] Hardware name: ASUSTeK COMPUTER INC. Z10PA-D8\nSeries/Z10PA-D8 Series, BIOS 3801 08/23/2019\n[ 411.479390] Workqueue: ksmbd-io handle_ksmbd_work [ksmbd]\n[ 411.479425] Call Trace:\n[ 411.479428] \n[ 411.479432] dump_stack_lvl+0x49/0x63\n[ 411.479444] print_report+0x171/0x4a8\n[ 411.479452] ? kasan_complete_mode_report_info+0x3c/0x200\n[ 411.479463] ? init_smb2_rsp_hdr+0x1e2/0x1f4 [ksmbd]\n[ 411.479497] kasan_report+0xb4/0x130\n[ 411.479503] ? init_smb2_rsp_hdr+0x1e2/0x1f4 [ksmbd]\n[ 411.479537] kasan_check_range+0x149/0x1e0\n[ 411.479543] memcpy+0x24/0x70\n[ 411.479550] init_smb2_rsp_hdr+0x1e2/0x1f4 [ksmbd]\n[ 411.479585] handle_ksmbd_work+0x109/0x760 [ksmbd]\n[ 411.479616] ? _raw_spin_unlock_irqrestore+0x50/0x50\n[ 411.479624] ? smb3_encrypt_resp+0x340/0x340 [ksmbd]\n[ 411.479656] process_one_work+0x49c/0x790\n[ 411.479667] worker_thread+0x2b1/0x6e0\n[ 411.479674] ? process_one_work+0x790/0x790\n[ 411.479680] kthread+0x177/0x1b0\n[ 411.479686] ? kthread_complete_and_exit+0x30/0x30\n[ 411.479692] ret_from_fork+0x22/0x30\n[ 411.479702] " } ], "metrics": [ { "cvssV3_1": { "version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H", "baseScore": 9.1, "baseSeverity": "CRITICAL" }, "scenarios": [ { "lang": "en", "value": "AV:N - ksmbd is the in-kernel SMB server listening on TCP/445; the vulnerable `init_smb2_rsp_hdr()` is reached directly from `ksmbd_conn_handler_loop()` processing bytes received from a remote peer. No local access is involved.\nAC:L - The attacker simply opens a TCP connection and sends one crafted SMB1-protocol PDU with a short RFC1002 length; the 16-byte read at fixed offset 52-68 occurs deterministically with no race and no dependence on conditions outside the attacker's control (the attacker even picks the allocation size, hence the slab bucket).\nPR:N - The defect triggers on the very first packet of a connection, in `init_rsp_hdr()` which runs before `ksmbd_verify_smb_message()`, before negotiate completes and before any session setup or credential validation. No authentication whatsoever is required.\nUI:N - The attacker drives the entire exchange by connecting to the SMB port and sending a packet; no action by any local user or administrator is needed.\nS:U - The out-of-bounds read and its consequences are confined to the kernel's own memory and the ksmbd server's security authority; no VM, IOMMU, or sandbox boundary is crossed.\nC:H - 16 bytes of adjacent kernel slab memory are memcpy'd into the response Signature field and transmitted back to the unauthenticated attacker via `ksmbd_conn_write()` (response length 64 includes offsets 52-68), and the attacker chooses `pdu_size` to select the slab cache and read distance — a repeatable, groomable disclosure of kernel heap contents including pointers and neighbouring session data.\nI:N - The defect is a read past the end of the request buffer; all writes (the response header memset/memcpy) stay within the 448-byte response allocation, so no out-of-bounds write or kernel data modification primitive exists.\nA:H - The read runs off the end of a tiny attacker-sized kmalloc object and is reported by KASAN as shown in the commit (a panic on `panic_on_warn` kernels), and on KFENCE/DEBUG_PAGEALLOC-enabled distro kernels it can fault on a guard page, oopsing the ksmbd workqueue thread; the attacker can retry indefinitely pre-authentication to hit that condition." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "fs/ksmbd/server.c", "fs/ksmbd/smb2pdu.c", "fs/ksmbd/smb_common.c", "fs/ksmbd/smb_common.h" ], "versions": [ { "version": "51a8534c0f35c0401e45f1055f914729cad98bf9", "lessThan": "921536046bd165efeb07beef5630aff35cd6a489", "status": "affected", "versionType": "git" }, { "version": "0b3ec5671ac06829ccebdaeec05acedfec327f42", "lessThan": "a8334a0c535d0f0b4d64926c8fe0922ed98f7d43", "status": "affected", "versionType": "git" }, { "version": "cc32cd98a0aee4cc3eb611cbce11795b1aaa738a", "lessThan": "99a51c673b1d2d0b5a972353401b77612d9cc713", "status": "affected", "versionType": "git" }, { "version": "39b291b86b5988bf8753c3874d5c773399d09b96", "lessThan": "dc8289f912387c3bcfbc5d2db29c8947fa207c11", "status": "affected", "versionType": "git" } ] }, { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "fs/ksmbd/server.c", "fs/ksmbd/smb2pdu.c", "fs/ksmbd/smb_common.c", "fs/ksmbd/smb_common.h" ], "versions": [ { "version": "5.15.105", "lessThan": "5.15.145", "status": "affected", "versionType": "semver" }, { "version": "6.1.22", "lessThan": "6.1.24", "status": "affected", "versionType": "semver" }, { "version": "6.2.9", "lessThan": "6.2.11", "status": "affected", "versionType": "semver" } ] } ], "cpeApplicability": [ { "nodes": [ { "operator": "OR", "negate": false, "cpeMatch": [ { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.15.105", "versionEndExcluding": "5.15.145" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.1.22", "versionEndExcluding": "6.1.24" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.2.9", "versionEndExcluding": "6.2.11" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/921536046bd165efeb07beef5630aff35cd6a489" }, { "url": "https://git.kernel.org/stable/c/a8334a0c535d0f0b4d64926c8fe0922ed98f7d43" }, { "url": "https://git.kernel.org/stable/c/99a51c673b1d2d0b5a972353401b77612d9cc713" }, { "url": "https://git.kernel.org/stable/c/dc8289f912387c3bcfbc5d2db29c8947fa207c11" } ], "title": "ksmbd: fix slab-out-of-bounds in init_smb2_rsp_hdr", "x_generator": { "engine": "bippy-1.2.0" } } } }