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]

No CVSS v4.0

Attack Vector Local

Attack Complexity Low

Privileges Required Low

Scope Unchanged

Confidentiality Impact High

Integrity Impact High

Availability Impact High

User Interaction None

No CVSS v3.0

No CVSS v2

This CVE is not in the KEV list.

The EPSS score is 0.00014.

Exploitation none

Automatable no

Technical Impact partial

Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).

Vendor Product Default status Versions
Linux Linux unaffected
Version Status Constraints
1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 affected < e8b8de17e164c9f1b7777f1c6f99d05539000036
1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 affected < 24219a977bfe3d658687e45615c70998acdbac5a
1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 affected < 9b6b2db77bc3121fe435f1d4b56e34de443bec75
1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 affected < 7d91adc0ccb060ce564103315189466eb822cc6a
1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 affected < 285e9210b1fab96a11c0be3ed5cea9dd48b6ac54
1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 affected < 7f221ccbee4ec662e2292d490a43ce6c314c4594
1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 affected < cc20226e218a2375d50dd9ac14fb4121b43375ff
1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 affected < 1f3e2e97c003f80c4b087092b225c8787ff91e4d
Linux Linux affected
Version Status Constraints
2.6.12 affected —
0 unaffected < 2.6.12
4.4.290 unaffected ≤ 4.4.*
4.9.288 unaffected ≤ 4.9.*
4.14.253 unaffected ≤ 4.14.*
4.19.214 unaffected ≤ 4.19.*
5.4.156 unaffected ≤ 5.4.*
5.10.76 unaffected ≤ 5.10.*
5.14.15 unaffected ≤ 5.14.*
5.15 unaffected ≤ *

Configuration 1 [-]

OR cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:5.15:rc1:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:5.15:rc2:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:5.15:rc3:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:5.15:rc4:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:5.15:rc5:*:*:*:*:*:*

No data.

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Fixes

Solution

No solution given by the vendor.

Workaround

No workaround given by the vendor.

References
Link Providers
https://git.kernel.org/stable/c/1f3e2e97c003f80c4b087092b225c8787ff91e4d cve-icon cve-icon
https://git.kernel.org/stable/c/24219a977bfe3d658687e45615c70998acdbac5a cve-icon cve-icon
https://git.kernel.org/stable/c/285e9210b1fab96a11c0be3ed5cea9dd48b6ac54 cve-icon cve-icon
https://git.kernel.org/stable/c/7d91adc0ccb060ce564103315189466eb822cc6a cve-icon cve-icon
https://git.kernel.org/stable/c/7f221ccbee4ec662e2292d490a43ce6c314c4594 cve-icon cve-icon
https://git.kernel.org/stable/c/9b6b2db77bc3121fe435f1d4b56e34de443bec75 cve-icon cve-icon
https://git.kernel.org/stable/c/cc20226e218a2375d50dd9ac14fb4121b43375ff cve-icon cve-icon
https://git.kernel.org/stable/c/e8b8de17e164c9f1b7777f1c6f99d05539000036 cve-icon cve-icon
https://lore.kernel.org/linux-cve-announce/2024062001-CVE-2021-4439-59ce@gregkh/T cve-icon
https://nvd.nist.gov/vuln/detail/CVE-2021-4439 cve-icon
https://www.cve.org/CVERecord?id=CVE-2021-4439 cve-icon
History

Fri, 01 Nov 2024 02:15:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Wed, 18 Sep 2024 17:00:00 +0000

Type Values Removed Values Added
First Time appeared Linux
Linux linux Kernel
Weaknesses CWE-129
CPEs cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:5.15:rc1:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:5.15:rc2:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:5.15:rc3:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:5.15:rc4:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:5.15:rc5:*:*:*:*:*:*
Vendors & Products Linux
Linux linux Kernel
Metrics cvssV3_1

{'score': 5.1, 'vector': 'CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:N/I:L/A:H'}

 cvssV3_1

{'score': 7.8, 'vector': 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H'}

Projects

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cve-icon MITRE

Status: PUBLISHED

Assigner: Linux

Published:

Updated: 2025-12-18T11:35:30.212Z

Reserved: 2024-06-20T12:07:18.155Z

Link: CVE-2021-4439

cve-icon Vulnrichment

Updated: 2024-08-03T17:30:07.335Z

cve-icon NVD

Status : Modified

Published: 2024-06-20T12:15:10.447

Modified: 2024-11-21T06:37:44.080

Link: CVE-2021-4439

cve-icon Redhat

Severity : Low

Publid Date: 2024-06-20T00:00:00Z

Links: CVE-2021-4439 - Bugzilla

cve-icon OpenCVE Enrichment

No data.

Weaknesses