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CVE-2021-4439 (GCVE-0-2021-4439)

Vulnerability from cvelistv5 – Published: 2024-06-20 12:07 – Updated: 2026-05-11 13:43
VLAI
Title
isdn: cpai: check ctr->cnr to avoid array index out of bound
Summary
In the Linux kernel, the following vulnerability has been resolved: isdn: cpai: check ctr->cnr to avoid array index out of bound The cmtp_add_connection() would add a cmtp session to a controller and run a kernel thread to process cmtp. __module_get(THIS_MODULE); session->task = kthread_run(cmtp_session, session, "kcmtpd_ctr_%d", session->num); During this process, the kernel thread would call detach_capi_ctr() to detach a register controller. if the controller was not attached yet, detach_capi_ctr() would trigger an array-index-out-bounds bug. [ 46.866069][ T6479] UBSAN: array-index-out-of-bounds in drivers/isdn/capi/kcapi.c:483:21 [ 46.867196][ T6479] index -1 is out of range for type 'capi_ctr *[32]' [ 46.867982][ T6479] CPU: 1 PID: 6479 Comm: kcmtpd_ctr_0 Not tainted 5.15.0-rc2+ #8 [ 46.869002][ T6479] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.14.0-2 04/01/2014 [ 46.870107][ T6479] Call Trace: [ 46.870473][ T6479] dump_stack_lvl+0x57/0x7d [ 46.870974][ T6479] ubsan_epilogue+0x5/0x40 [ 46.871458][ T6479] __ubsan_handle_out_of_bounds.cold+0x43/0x48 [ 46.872135][ T6479] detach_capi_ctr+0x64/0xc0 [ 46.872639][ T6479] cmtp_session+0x5c8/0x5d0 [ 46.873131][ T6479] ? __init_waitqueue_head+0x60/0x60 [ 46.873712][ T6479] ? cmtp_add_msgpart+0x120/0x120 [ 46.874256][ T6479] kthread+0x147/0x170 [ 46.874709][ T6479] ? set_kthread_struct+0x40/0x40 [ 46.875248][ T6479] ret_from_fork+0x1f/0x30 [ 46.875773][ T6479]
Severity
No CVSS data available.
SSVC
Exploitation: none Automatable: no Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2024-06-20 14:46 UTC
Assigner
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 , < e8b8de17e164c9f1b7777f1c6f99d05539000036 (git)
Affected: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 , < 24219a977bfe3d658687e45615c70998acdbac5a (git)
Affected: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 , < 9b6b2db77bc3121fe435f1d4b56e34de443bec75 (git)
Affected: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 , < 7d91adc0ccb060ce564103315189466eb822cc6a (git)
Affected: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 , < 285e9210b1fab96a11c0be3ed5cea9dd48b6ac54 (git)
Affected: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 , < 7f221ccbee4ec662e2292d490a43ce6c314c4594 (git)
Affected: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 , < cc20226e218a2375d50dd9ac14fb4121b43375ff (git)
Affected: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 , < 1f3e2e97c003f80c4b087092b225c8787ff91e4d (git)
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Linux Linux Affected: 2.6.12
Unaffected: 0 , < 2.6.12 (semver)
Unaffected: 4.4.290 , ≤ 4.4.* (semver)
Unaffected: 4.9.288 , ≤ 4.9.* (semver)
Unaffected: 4.14.253 , ≤ 4.14.* (semver)
Unaffected: 4.19.214 , ≤ 4.19.* (semver)
Unaffected: 5.4.156 , ≤ 5.4.* (semver)
Unaffected: 5.10.76 , ≤ 5.10.* (semver)
Unaffected: 5.14.15 , ≤ 5.14.* (semver)
Unaffected: 5.15 , ≤ * (original_commit_for_fix)
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          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nisdn: cpai: check ctr-\u003ecnr to avoid array index out of bound\n\nThe cmtp_add_connection() would add a cmtp session to a controller\nand run a kernel thread to process cmtp.\n\n\t__module_get(THIS_MODULE);\n\tsession-\u003etask = kthread_run(cmtp_session, session, \"kcmtpd_ctr_%d\",\n\t\t\t\t\t\t\t\tsession-\u003enum);\n\nDuring this process, the kernel thread would call detach_capi_ctr()\nto detach a register controller. if the controller\nwas not attached yet, detach_capi_ctr() would\ntrigger an array-index-out-bounds bug.\n\n[   46.866069][ T6479] UBSAN: array-index-out-of-bounds in\ndrivers/isdn/capi/kcapi.c:483:21\n[   46.867196][ T6479] index -1 is out of range for type \u0027capi_ctr *[32]\u0027\n[   46.867982][ T6479] CPU: 1 PID: 6479 Comm: kcmtpd_ctr_0 Not tainted\n5.15.0-rc2+ #8\n[   46.869002][ T6479] Hardware name: QEMU Standard PC (i440FX + PIIX,\n1996), BIOS 1.14.0-2 04/01/2014\n[   46.870107][ T6479] Call Trace:\n[   46.870473][ T6479]  dump_stack_lvl+0x57/0x7d\n[   46.870974][ T6479]  ubsan_epilogue+0x5/0x40\n[   46.871458][ T6479]  __ubsan_handle_out_of_bounds.cold+0x43/0x48\n[   46.872135][ T6479]  detach_capi_ctr+0x64/0xc0\n[   46.872639][ T6479]  cmtp_session+0x5c8/0x5d0\n[   46.873131][ T6479]  ? __init_waitqueue_head+0x60/0x60\n[   46.873712][ T6479]  ? cmtp_add_msgpart+0x120/0x120\n[   46.874256][ T6479]  kthread+0x147/0x170\n[   46.874709][ T6479]  ? set_kthread_struct+0x40/0x40\n[   46.875248][ T6479]  ret_from_fork+0x1f/0x30\n[   46.875773][ T6479]"
        },
        {
          "lang": "es",
          "value": "En el kernel de Linux, se resolvi\u00f3 la siguiente vulnerabilidad: isdn: cpai: verifique ctr-\u0026gt;cnr para evitar que el \u00edndice de matriz est\u00e9 fuera de l\u00edmite. cmtp_add_connection() agregar\u00eda una sesi\u00f3n cmtp a un controlador y ejecutar\u00eda un subproceso del kernel para procesar cmtp. __module_get(ESTE_M\u00d3DULO); sesi\u00f3n-\u0026gt;tarea = kthread_run(cmtp_session, sesi\u00f3n, \"kcmtpd_ctr_%d\", sesi\u00f3n-\u0026gt;num); Durante este proceso, el hilo del n\u00facleo llamar\u00eda a detach_capi_ctr() para desconectar un controlador de registro. Si el controlador a\u00fan no estaba conectado, detach_capi_ctr() desencadenar\u00eda un error de los l\u00edmites de \u00edndice de matriz. [ 46.866069][ T6479] UBSAN: \u00edndice de matriz fuera de los l\u00edmites en drivers/isdn/capi/kcapi.c:483:21 [ 46.867196][ T6479] el \u00edndice -1 est\u00e1 fuera de rango para el tipo \u0027capi_ctr *[ 32]\u0027 [ 46.867982][ T6479] CPU: 1 PID: 6479 Comm: kcmtpd_ctr_0 No contaminado 5.15.0-rc2+ #8 [ 46.869002][ T6479] Nombre de hardware: PC est\u00e1ndar QEMU (i440FX + PIIX, 1996), BIOS 1.14. 0-2 01/04/2014 [ 46.870107][ T6479] Seguimiento de llamadas: [ 46.870473][ T6479] dump_stack_lvl+0x57/0x7d [ 46.870974][ T6479] ubsan_epilogue+0x5/0x40 [ 46.871458][ T6479 ] __ubsan_handle_out_of_bounds.cold+0x43 /0x48 [ 46.872135][ T6479] detach_capi_ctr+0x64/0xc0 [ 46.872639][ T6479] cmtp_session+0x5c8/0x5d0 [ 46.873131][ T6479] ? __init_waitqueue_head+0x60/0x60 [ 46.873712][ T6479] ? cmtp_add_msgpart+0x120/0x120 [ 46.874256][ T6479] kthread+0x147/0x170 [ 46.874709][ T6479] ? set_kthread_struct+0x40/0x40 [ 46.875248][ T6479] ret_from_fork+0x1f/0x30 [ 46.875773][ T6479]"
        }
      ],
      "id": "CVE-2021-4439",
      "lastModified": "2024-11-21T06:37:44.080",
      "metrics": {
        "cvssMetricV31": [
          {
            "cvssData": {
              "attackComplexity": "LOW",
              "attackVector": "LOCAL",
              "availabilityImpact": "HIGH",
              "baseScore": 7.8,
              "baseSeverity": "HIGH",
              "confidentialityImpact": "HIGH",
              "integrityImpact": "HIGH",
              "privilegesRequired": "LOW",
              "scope": "UNCHANGED",
              "userInteraction": "NONE",
              "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
              "version": "3.1"
            },
            "exploitabilityScore": 1.8,
            "impactScore": 5.9,
            "source": "nvd@nist.gov",
            "type": "Primary"
          }
        ]
      },
      "published": "2024-06-20T12:15:10.447",
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      "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "vulnStatus": "Modified",
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          "description": [
            {
              "lang": "en",
              "value": "CWE-129"
            }
          ],
          "source": "nvd@nist.gov",
          "type": "Primary"
        }
      ]
    },
    "nvd": {
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                    "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2",
                    "versionType": "git"
                  }
                ]
              },
              {
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                "product": "Linux",
                "programFiles": [
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                ],
                "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
                "vendor": "Linux",
                "versions": [
                  {
                    "status": "affected",
                    "version": "2.6.12"
                  },
                  {
                    "lessThan": "2.6.12",
                    "status": "unaffected",
                    "version": "0",
                    "versionType": "semver"
                  },
                  {
                    "lessThanOrEqual": "4.4.*",
                    "status": "unaffected",
                    "version": "4.4.290",
                    "versionType": "semver"
                  },
                  {
                    "lessThanOrEqual": "4.9.*",
                    "status": "unaffected",
                    "version": "4.9.288",
                    "versionType": "semver"
                  },
                  {
                    "lessThanOrEqual": "4.14.*",
                    "status": "unaffected",
                    "version": "4.14.253",
                    "versionType": "semver"
                  },
                  {
                    "lessThanOrEqual": "4.19.*",
                    "status": "unaffected",
                    "version": "4.19.214",
                    "versionType": "semver"
                  },
                  {
                    "lessThanOrEqual": "5.4.*",
                    "status": "unaffected",
                    "version": "5.4.156",
                    "versionType": "semver"
                  },
                  {
                    "lessThanOrEqual": "5.10.*",
                    "status": "unaffected",
                    "version": "5.10.76",
                    "versionType": "semver"
                  },
                  {
                    "lessThanOrEqual": "5.14.*",
                    "status": "unaffected",
                    "version": "5.14.15",
                    "versionType": "semver"
                  },
                  {
                    "lessThanOrEqual": "*",
                    "status": "unaffected",
                    "version": "5.15",
                    "versionType": "original_commit_for_fix"
                  }
                ]
              }
            ],
            "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
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        ],
        "configurations": [
          {
            "nodes": [
              {
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                    "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                    "matchCriteriaId": "C56A8089-600C-4D13-B0BD-0B3B87CAAAEC",
                    "versionEndExcluding": "4.4.290",
                    "vulnerable": true
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                    "matchCriteriaId": "F99C0BFE-2803-4525-BA2B-EA4F42F8CADE",
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                    "matchCriteriaId": "0460DA88-8FE1-46A2-9DDA-1F1ABA552E71",
                    "vulnerable": true
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                    "matchCriteriaId": "AF55383D-4DF2-45DC-93F7-571F4F978EAB",
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        ],
        "cveTags": [],
        "descriptions": [
          {
            "lang": "en",
            "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nisdn: cpai: check ctr-\u003ecnr to avoid array index out of bound\n\nThe cmtp_add_connection() would add a cmtp session to a controller\nand run a kernel thread to process cmtp.\n\n\t__module_get(THIS_MODULE);\n\tsession-\u003etask = kthread_run(cmtp_session, session, \"kcmtpd_ctr_%d\",\n\t\t\t\t\t\t\t\tsession-\u003enum);\n\nDuring this process, the kernel thread would call detach_capi_ctr()\nto detach a register controller. if the controller\nwas not attached yet, detach_capi_ctr() would\ntrigger an array-index-out-bounds bug.\n\n[   46.866069][ T6479] UBSAN: array-index-out-of-bounds in\ndrivers/isdn/capi/kcapi.c:483:21\n[   46.867196][ T6479] index -1 is out of range for type \u0027capi_ctr *[32]\u0027\n[   46.867982][ T6479] CPU: 1 PID: 6479 Comm: kcmtpd_ctr_0 Not tainted\n5.15.0-rc2+ #8\n[   46.869002][ T6479] Hardware name: QEMU Standard PC (i440FX + PIIX,\n1996), BIOS 1.14.0-2 04/01/2014\n[   46.870107][ T6479] Call Trace:\n[   46.870473][ T6479]  dump_stack_lvl+0x57/0x7d\n[   46.870974][ T6479]  ubsan_epilogue+0x5/0x40\n[   46.871458][ T6479]  __ubsan_handle_out_of_bounds.cold+0x43/0x48\n[   46.872135][ T6479]  detach_capi_ctr+0x64/0xc0\n[   46.872639][ T6479]  cmtp_session+0x5c8/0x5d0\n[   46.873131][ T6479]  ? __init_waitqueue_head+0x60/0x60\n[   46.873712][ T6479]  ? cmtp_add_msgpart+0x120/0x120\n[   46.874256][ T6479]  kthread+0x147/0x170\n[   46.874709][ T6479]  ? set_kthread_struct+0x40/0x40\n[   46.875248][ T6479]  ret_from_fork+0x1f/0x30\n[   46.875773][ T6479]"
          },
          {
            "lang": "es",
            "value": "En el kernel de Linux, se resolvi\u00f3 la siguiente vulnerabilidad: isdn: cpai: verifique ctr-\u0026gt;cnr para evitar que el \u00edndice de matriz est\u00e9 fuera de l\u00edmite. cmtp_add_connection() agregar\u00eda una sesi\u00f3n cmtp a un controlador y ejecutar\u00eda un subproceso del kernel para procesar cmtp. __module_get(ESTE_M\u00d3DULO); sesi\u00f3n-\u0026gt;tarea = kthread_run(cmtp_session, sesi\u00f3n, \"kcmtpd_ctr_%d\", sesi\u00f3n-\u0026gt;num); Durante este proceso, el hilo del n\u00facleo llamar\u00eda a detach_capi_ctr() para desconectar un controlador de registro. Si el controlador a\u00fan no estaba conectado, detach_capi_ctr() desencadenar\u00eda un error de los l\u00edmites de \u00edndice de matriz. [ 46.866069][ T6479] UBSAN: \u00edndice de matriz fuera de los l\u00edmites en drivers/isdn/capi/kcapi.c:483:21 [ 46.867196][ T6479] el \u00edndice -1 est\u00e1 fuera de rango para el tipo \u0027capi_ctr *[ 32]\u0027 [ 46.867982][ T6479] CPU: 1 PID: 6479 Comm: kcmtpd_ctr_0 No contaminado 5.15.0-rc2+ #8 [ 46.869002][ T6479] Nombre de hardware: PC est\u00e1ndar QEMU (i440FX + PIIX, 1996), BIOS 1.14. 0-2 01/04/2014 [ 46.870107][ T6479] Seguimiento de llamadas: [ 46.870473][ T6479] dump_stack_lvl+0x57/0x7d [ 46.870974][ T6479] ubsan_epilogue+0x5/0x40 [ 46.871458][ T6479 ] __ubsan_handle_out_of_bounds.cold+0x43 /0x48 [ 46.872135][ T6479] detach_capi_ctr+0x64/0xc0 [ 46.872639][ T6479] cmtp_session+0x5c8/0x5d0 [ 46.873131][ T6479] ? __init_waitqueue_head+0x60/0x60 [ 46.873712][ T6479] ? cmtp_add_msgpart+0x120/0x120 [ 46.874256][ T6479] kthread+0x147/0x170 [ 46.874709][ T6479] ? set_kthread_struct+0x40/0x40 [ 46.875248][ T6479] ret_from_fork+0x1f/0x30 [ 46.875773][ T6479]"
          }
        ],
        "id": "CVE-2021-4439",
        "lastModified": "2026-06-17T04:19:45.633",
        "metrics": {
          "cvssMetricV31": [
            {
              "cvssData": {
                "attackComplexity": "LOW",
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                "availabilityImpact": "HIGH",
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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.

Sightings

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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.


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Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.