FKIE_CVE-2021-4439
Vulnerability from fkie_nvd - Published: 2024-06-20 12:15 - Updated: 2026-06-17 04:19
Severity
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]
References
Impacted products
| Vendor | Product | Version | |
|---|---|---|---|
| linux | linux_kernel | * | |
| linux | linux_kernel | * | |
| linux | linux_kernel | * | |
| linux | linux_kernel | * | |
| linux | linux_kernel | * | |
| linux | linux_kernel | * | |
| linux | linux_kernel | * | |
| linux | linux_kernel | 5.15 | |
| linux | linux_kernel | 5.15 | |
| linux | linux_kernel | 5.15 | |
| linux | linux_kernel | 5.15 | |
| linux | linux_kernel | 5.15 |
{
"affected": [
{
"affectedData": [
{
"defaultStatus": "unaffected",
"product": "Linux",
"programFiles": [
"drivers/isdn/capi/kcapi.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
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"versionType": "git"
},
{
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"versionType": "git"
},
{
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"status": "affected",
"version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2",
"versionType": "git"
},
{
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"status": "affected",
"version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2",
"versionType": "git"
},
{
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"versionType": "git"
},
{
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"status": "affected",
"version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2",
"versionType": "git"
},
{
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"status": "affected",
"version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2",
"versionType": "git"
},
{
"lessThan": "1f3e2e97c003f80c4b087092b225c8787ff91e4d",
"status": "affected",
"version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2",
"versionType": "git"
}
]
},
{
"defaultStatus": "affected",
"product": "Linux",
"programFiles": [
"drivers/isdn/capi/kcapi.c"
],
"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"
}
],
"configurations": [
{
"nodes": [
{
"cpeMatch": [
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"matchCriteriaId": "C56A8089-600C-4D13-B0BD-0B3B87CAAAEC",
"versionEndExcluding": "4.4.290",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"matchCriteriaId": "F99C0BFE-2803-4525-BA2B-EA4F42F8CADE",
"versionEndExcluding": "4.9.288",
"versionStartIncluding": "4.5",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"matchCriteriaId": "1830428A-CB40-4E7F-A4F9-177A0B9614D2",
"versionEndExcluding": "4.14.253",
"versionStartIncluding": "4.10",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"matchCriteriaId": "8491C8F9-93D0-4314-BD59-65E3038494EA",
"versionEndExcluding": "4.19.214",
"versionStartIncluding": "4.15",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"matchCriteriaId": "03015A9C-56AA-4210-9491-CF2FB0F45B9A",
"versionEndExcluding": "5.4.156",
"versionStartIncluding": "4.20",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"matchCriteriaId": "E61528CE-9083-425B-AE36-3791232BF780",
"versionEndExcluding": "5.10.76",
"versionStartIncluding": "5.5",
"vulnerable": true
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{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"matchCriteriaId": "63BD46C4-473F-45F9-93E9-F67D955321D8",
"versionEndExcluding": "5.14.15",
"versionStartIncluding": "5.11",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:5.15:rc1:*:*:*:*:*:*",
"matchCriteriaId": "E46C74C6-B76B-4C94-A6A4-FD2FFF62D644",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:5.15:rc2:*:*:*:*:*:*",
"matchCriteriaId": "60134C3A-06E4-48C1-B04F-2903732A4E56",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:5.15:rc3:*:*:*:*:*:*",
"matchCriteriaId": "0460DA88-8FE1-46A2-9DDA-1F1ABA552E71",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:5.15:rc4:*:*:*:*:*:*",
"matchCriteriaId": "AF55383D-4DF2-45DC-93F7-571F4F978EAB",
"vulnerable": true
},
{
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"matchCriteriaId": "9E9481B2-8AA6-4CBD-B5D3-C10F51FF6D01",
"vulnerable": true
}
],
"negate": false,
"operator": "OR"
}
]
}
],
"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",
"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"
}
],
"ssvcV203": [
{
"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
"ssvcData": {
"id": "CVE-2021-4439",
"options": [
{
"exploitation": "none"
},
{
"automatable": "no"
},
{
"technicalImpact": "partial"
}
],
"role": "CISA Coordinator",
"timestamp": "2024-06-20T14:46:11.140255Z",
"version": "2.0.3"
}
}
]
},
"published": "2024-06-20T12:15:10.447",
"references": [
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"tags": [
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"url": "https://git.kernel.org/stable/c/1f3e2e97c003f80c4b087092b225c8787ff91e4d"
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},
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{
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"tags": [
"Patch"
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},
{
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},
{
"source": "af854a3a-2127-422b-91ae-364da2661108",
"tags": [
"Patch"
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"url": "https://git.kernel.org/stable/c/9b6b2db77bc3121fe435f1d4b56e34de443bec75"
},
{
"source": "af854a3a-2127-422b-91ae-364da2661108",
"tags": [
"Patch"
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"url": "https://git.kernel.org/stable/c/cc20226e218a2375d50dd9ac14fb4121b43375ff"
},
{
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"tags": [
"Patch"
],
"url": "https://git.kernel.org/stable/c/e8b8de17e164c9f1b7777f1c6f99d05539000036"
}
],
"sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"vulnStatus": "Modified",
"weaknesses": [
{
"description": [
{
"lang": "en",
"value": "CWE-129"
}
],
"source": "nvd@nist.gov",
"type": "Primary"
}
]
}
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Experimental. This forecast is provided for visualization only and may change without notice. Do not use it for operational decisions.
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.
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The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the
vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base
model, served locally by ML-Gateway.
They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.
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