CVE-2023-54203 (GCVE-0-2023-54203)

Vulnerability from cvelistv5 – Published: 2025-12-30 12:09 – Updated: 2026-08-05 09:18
VLAI
Title
ksmbd: fix slab-out-of-bounds in init_smb2_rsp_hdr
Summary
In the Linux kernel, the following vulnerability has been resolved: ksmbd: fix slab-out-of-bounds in init_smb2_rsp_hdr When smb1 mount fails, KASAN detect slab-out-of-bounds in init_smb2_rsp_hdr like the following one. For smb1 negotiate(56bytes) , init_smb2_rsp_hdr() for smb2 is called. The issue occurs while handling smb1 negotiate as smb2 server operations. Add smb server operations for smb1 (get_cmd_val, init_rsp_hdr, allocate_rsp_buf, check_user_session) to handle smb1 negotiate so that smb2 server operation does not handle it. [ 411.400423] CIFS: VFS: Use of the less secure dialect vers=1.0 is not recommended unless required for access to very old servers [ 411.400452] CIFS: Attempting to mount \\192.168.45.139\homes [ 411.479312] ksmbd: init_smb2_rsp_hdr : 492 [ 411.479323] ================================================================== [ 411.479327] BUG: KASAN: slab-out-of-bounds in init_smb2_rsp_hdr+0x1e2/0x1f4 [ksmbd] [ 411.479369] Read of size 16 at addr ffff888488ed0734 by task kworker/14:1/199 [ 411.479379] CPU: 14 PID: 199 Comm: kworker/14:1 Tainted: G OE 6.1.21 #3 [ 411.479386] Hardware name: ASUSTeK COMPUTER INC. Z10PA-D8 Series/Z10PA-D8 Series, BIOS 3801 08/23/2019 [ 411.479390] Workqueue: ksmbd-io handle_ksmbd_work [ksmbd] [ 411.479425] Call Trace: [ 411.479428] <TASK> [ 411.479432] dump_stack_lvl+0x49/0x63 [ 411.479444] print_report+0x171/0x4a8 [ 411.479452] ? kasan_complete_mode_report_info+0x3c/0x200 [ 411.479463] ? init_smb2_rsp_hdr+0x1e2/0x1f4 [ksmbd] [ 411.479497] kasan_report+0xb4/0x130 [ 411.479503] ? init_smb2_rsp_hdr+0x1e2/0x1f4 [ksmbd] [ 411.479537] kasan_check_range+0x149/0x1e0 [ 411.479543] memcpy+0x24/0x70 [ 411.479550] init_smb2_rsp_hdr+0x1e2/0x1f4 [ksmbd] [ 411.479585] handle_ksmbd_work+0x109/0x760 [ksmbd] [ 411.479616] ? _raw_spin_unlock_irqrestore+0x50/0x50 [ 411.479624] ? smb3_encrypt_resp+0x340/0x340 [ksmbd] [ 411.479656] process_one_work+0x49c/0x790 [ 411.479667] worker_thread+0x2b1/0x6e0 [ 411.479674] ? process_one_work+0x790/0x790 [ 411.479680] kthread+0x177/0x1b0 [ 411.479686] ? kthread_complete_and_exit+0x30/0x30 [ 411.479692] ret_from_fork+0x22/0x30 [ 411.479702] </TASK>
Severity
9.1 (Critical)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H
Assigner
References
Impacted products
Vendor Product Version
Linux Linux Affected: 51a8534c0f35c0401e45f1055f914729cad98bf9 , < 921536046bd165efeb07beef5630aff35cd6a489 (git)
Affected: 0b3ec5671ac06829ccebdaeec05acedfec327f42 , < a8334a0c535d0f0b4d64926c8fe0922ed98f7d43 (git)
Affected: cc32cd98a0aee4cc3eb611cbce11795b1aaa738a , < 99a51c673b1d2d0b5a972353401b77612d9cc713 (git)
Affected: 39b291b86b5988bf8753c3874d5c773399d09b96 , < dc8289f912387c3bcfbc5d2db29c8947fa207c11 (git)
Create a notification for this product.
Linux Linux Affected: 5.15.105 , < 5.15.145 (semver)
Affected: 6.1.22 , < 6.1.24 (semver)
Affected: 6.2.9 , < 6.2.11 (semver)
Create a notification for this product.
Show details on NVD website
To clipboard 

{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "fs/ksmbd/server.c",
            "fs/ksmbd/smb2pdu.c",
            "fs/ksmbd/smb_common.c",
            "fs/ksmbd/smb_common.h"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "921536046bd165efeb07beef5630aff35cd6a489",
              "status": "affected",
              "version": "51a8534c0f35c0401e45f1055f914729cad98bf9",
              "versionType": "git"
            },
            {
              "lessThan": "a8334a0c535d0f0b4d64926c8fe0922ed98f7d43",
              "status": "affected",
              "version": "0b3ec5671ac06829ccebdaeec05acedfec327f42",
              "versionType": "git"
            },
            {
              "lessThan": "99a51c673b1d2d0b5a972353401b77612d9cc713",
              "status": "affected",
              "version": "cc32cd98a0aee4cc3eb611cbce11795b1aaa738a",
              "versionType": "git"
            },
            {
              "lessThan": "dc8289f912387c3bcfbc5d2db29c8947fa207c11",
              "status": "affected",
              "version": "39b291b86b5988bf8753c3874d5c773399d09b96",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "fs/ksmbd/server.c",
            "fs/ksmbd/smb2pdu.c",
            "fs/ksmbd/smb_common.c",
            "fs/ksmbd/smb_common.h"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "5.15.145",
              "status": "affected",
              "version": "5.15.105",
              "versionType": "semver"
            },
            {
              "lessThan": "6.1.24",
              "status": "affected",
              "version": "6.1.22",
              "versionType": "semver"
            },
            {
              "lessThan": "6.2.11",
              "status": "affected",
              "version": "6.2.9",
              "versionType": "semver"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "5.15.145",
                  "versionStartIncluding": "5.15.105",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.1.24",
                  "versionStartIncluding": "6.1.22",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.2.11",
                  "versionStartIncluding": "6.2.9",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "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]  \u003cTASK\u003e\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]  \u003c/TASK\u003e"
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 9.1,
            "baseSeverity": "CRITICAL",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H",
            "version": "3.1"
          },
          "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\u0027s 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\u0027s own memory and the ksmbd server\u0027s security authority; no VM, IOMMU, or sandbox boundary is crossed.\nC:H - 16 bytes of adjacent kernel slab memory are memcpy\u0027d 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 \u2014 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."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-05T09:18:01.954Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "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"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2023-54203",
    "datePublished": "2025-12-30T12:09:07.538Z",
    "dateReserved": "2025-12-30T12:06:44.499Z",
    "dateUpdated": "2026-08-05T09:18:01.954Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
    "epss": {
      "cve": "CVE-2023-54203",
      "date": "2026-08-10",
      "epss": "0.00475",
      "percentile": "0.3863"
    },
    "nvd": "{\"cve\":{\"id\":\"CVE-2023-54203\",\"sourceIdentifier\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"published\":\"2025-12-30T13:16:08.420\",\"lastModified\":\"2026-08-04T11:16:36.580\",\"vulnStatus\":\"Deferred\",\"cveTags\":[],\"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]  \u003cTASK\u003e\\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]  \u003c/TASK\u003e\"}],\"affected\":[{\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"affectedData\":[{\"vendor\":\"Linux\",\"product\":\"Linux\",\"defaultStatus\":\"unaffected\",\"programFiles\":[\"fs/ksmbd/server.c\",\"fs/ksmbd/smb2pdu.c\",\"fs/ksmbd/smb_common.c\",\"fs/ksmbd/smb_common.h\"],\"repo\":\"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\"versions\":[{\"version\":\"51a8534c0f35c0401e45f1055f914729cad98bf9\",\"lessThan\":\"921536046bd165efeb07beef5630aff35cd6a489\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"0b3ec5671ac06829ccebdaeec05acedfec327f42\",\"lessThan\":\"a8334a0c535d0f0b4d64926c8fe0922ed98f7d43\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"cc32cd98a0aee4cc3eb611cbce11795b1aaa738a\",\"lessThan\":\"99a51c673b1d2d0b5a972353401b77612d9cc713\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"39b291b86b5988bf8753c3874d5c773399d09b96\",\"lessThan\":\"dc8289f912387c3bcfbc5d2db29c8947fa207c11\",\"versionType\":\"git\",\"status\":\"affected\"}]},{\"vendor\":\"Linux\",\"product\":\"Linux\",\"defaultStatus\":\"unaffected\",\"programFiles\":[\"fs/ksmbd/server.c\",\"fs/ksmbd/smb2pdu.c\",\"fs/ksmbd/smb_common.c\",\"fs/ksmbd/smb_common.h\"],\"repo\":\"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\"versions\":[{\"version\":\"5.15.105\",\"lessThan\":\"5.15.145\",\"versionType\":\"semver\",\"status\":\"affected\"},{\"version\":\"6.1.22\",\"lessThan\":\"6.1.24\",\"versionType\":\"semver\",\"status\":\"affected\"},{\"version\":\"6.2.9\",\"lessThan\":\"6.2.11\",\"versionType\":\"semver\",\"status\":\"affected\"}]}]}],\"metrics\":{\"cvssMetricV31\":[{\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"type\":\"Secondary\",\"cvssData\":{\"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\",\"attackVector\":\"NETWORK\",\"attackComplexity\":\"LOW\",\"privilegesRequired\":\"NONE\",\"userInteraction\":\"NONE\",\"scope\":\"UNCHANGED\",\"confidentialityImpact\":\"HIGH\",\"integrityImpact\":\"NONE\",\"availabilityImpact\":\"HIGH\"},\"exploitabilityScore\":3.9,\"impactScore\":5.2}]},\"references\":[{\"url\":\"https://git.kernel.org/stable/c/921536046bd165efeb07beef5630aff35cd6a489\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/99a51c673b1d2d0b5a972353401b77612d9cc713\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/a8334a0c535d0f0b4d64926c8fe0922ed98f7d43\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/dc8289f912387c3bcfbc5d2db29c8947fa207c11\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"}]}}",
    "redhat_vex": {
      "aggregate_severity": "None",
      "current_release_date": "2026-06-30T10:29:48+00:00",
      "cve": "CVE-2023-54203",
      "id": "CVE-2023-54203",
      "initial_release_date": "2023-01-01T00:00:00+00:00",
      "product_status:known_not_affected": "274",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: ksmbd: fix slab-out-of-bounds in init_smb2_rsp_hdr",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2023/cve-2023-54203.json",
      "version": "3"
    },
    "suse_vex": {
      "aggregate_severity": "moderate",
      "current_release_date": "2026-08-05T01:02:38Z",
      "cve": "CVE-2023-54203",
      "id": "CVE-2023-54203",
      "initial_release_date": "2025-12-31T00:28:34Z",
      "product_status:known_not_affected": "453",
      "source": "SUSE CSAF VEX",
      "status": "interim",
      "title": "SUSE CVE CVE-2023-54203",
      "url": "https://ftp.suse.com/pub/projects/security/csaf-vex/cve-2023-54203.json",
      "version": "11"
    }
  }
}



Log in or create an account to share your comment.




Tags
Taxonomy of the tags.





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.

Sightings

Author Source Type Date Other

Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
  • Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.


Detection rules are retrieved from Rulezet.