CVE-2021-4439

Advisory lineage Upstream: 0 Downstream: 14
Modified
Published: 20 Jun 2024, 12:07
Last modified:11 May 2026, 13:43

Vulnerability Summary

Overall Risk (default)
medium
31/100
CVSS Score
7.8 HIGH
v3.1 (nvd)
EPSS Score
0.02% LOW
0% probability 0.00%
KEV
Not listed
Ransomware
No reports
Public exploits
None found
Dark Web
Not detected

Timeline

20 Jun 2024, 12:07
Published
Vulnerability first disclosed
11 May 2026, 13:43
Last Modified
Vulnerability information updated

Description

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]

CVSS Metrics

  • v3.1•HIGH•Score: 7.8CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

EPSS Trends

Current EPSS score: 0.02%• Percentile: 5%

Techniques & Countermeasures

  • CWE-129•Improper Validation of Array Index

    The product uses untrusted input when calculating or using an array index, but the product does not validate or incorrectly validates the index to ensure the index references a valid position within the array.

Affected Systems

  • linux•linux

    ≥ 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, < e8b8de17e164c9f1b7777f1c6f99d05539000036 | ≥ 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, < 24219a977bfe3d658687e45615c70998acdbac5a | ≥ 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, < 9b6b2db77bc3121fe435f1d4b56e34de443bec75 | ≥ 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, < 7d91adc0ccb060ce564103315189466eb822cc6a | ≥ 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, < 285e9210b1fab96a11c0be3ed5cea9dd48b6ac54 | ≥ 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, < 7f221ccbee4ec662e2292d490a43ce6c314c4594 | ≥ 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, < cc20226e218a2375d50dd9ac14fb4121b43375ff | ≥ 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, < 1f3e2e97c003f80c4b087092b225c8787ff91e4d | 2.6.12

  • linux•linux_kernel

    < 4.4.290 | ≥ 4.5, < 4.9.288 | ≥ 4.10, < 4.14.253 | ≥ 4.15, < 4.19.214 | ≥ 4.20, < 5.4.156 | ≥ 5.5, < 5.10.76 | ≥ 5.11, < 5.14.15 | 5.15:rc1 | 5.15:rc2 | 5.15:rc3 | 5.15:rc4 | 5.15:rc5

References (8)