Vulnerability-Lookup

BDU:2025-14236 (CVE-2021-47451)

Vulnerability from fstec – Published: 2025-11-16 – Updated: 2025-11-16 – View on bdu.fstec.ru Fixed

Title

Уязвимость функции idletimer_tg_create() модуля net/netfilter/xt_IDLETIMER.c компонента netfilter ядра операционной системы Linux, позволяющая нарушителю вызвать отказ в обслуживании

Summary

Уязвимость функции idletimer_tg_create() модуля net/netfilter/xt_IDLETIMER.c компонента netfilter ядра операционной системы Linux связана с использованием неинициализированных переменных. Эксплуатация уязвимости может позволить нарушителю вызвать отказ в обслуживании

Severity

4.6 (Medium) CVSS 2.0


                      
                        AV:L/AC:L/Au:S/C:N/I:N/A:C

5.5 (Medium) CVSS 3.1


                      
                        CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Class

Code vulnerability

Status

Confirmed by the vendor

Exploitation

Data structure manipulation, Resource manipulation

Incidents

Being clarified

Remediation

Software update

CWE

CWE-457 - Использование неинициализированной переменной
CWE-908 - Использование неинициализированного ресурса

Aliases

CVE-2021-47451

References

8 references

URL
https://www.cve.org/CVERecord?id=CVE-2021-47451
https://git.kernel.org/stable/c/2a670c323055282c9b72794a491d53cef86bbeaf
https://git.kernel.org/stable/c/cae7cab804c943d723d52724a3aeb07a3f4a2650
https://lore.kernel.org/linux-cve-announce/2024052242-CVE-2021-47451-72c7@gregkh/
https://git.kernel.org/linus/902c0b1887522a099aa4e1e6b4b476c2fe5dd13e
https://git.linuxtesting.ru/pub/scm/linux/kernel/git/lvc/linux-stable.git/commi…
https://kernel.org/pub/linux/kernel/v5.x/ChangeLog-5.10.76
https://kernel.org/pub/linux/kernel/v5.x/ChangeLog-5.14.15

Impacted products

1 product from 1 vendor

Vendors

Сообщество свободного программного обеспечения

Products

Linux

Versions

от 5.11 до 5.14.14 включительно (Linux), от 5.7 до 5.10.75 включительно (Linux)

Product types

Operating system

Platforms

Сообщество свободного программного обеспечения Linux от 5.11 до 5.14.14 включительно, Сообщество свободного программного обеспечения Linux от 5.7 до 5.10.75 включительно

Mitigations

В условиях отсутствия обновлений безопасности от производителя рекомендуется придерживаться "Рекомендаций по безопасной настройке операционных систем LINUX", изложенных в методическом документе ФСТЭК России, утверждённом 25 декабря 2022 года. Использование рекомендаций: Для Linux: https://git.kernel.org/stable/c/2a670c323055282c9b72794a491d53cef86bbeaf https://git.kernel.org/stable/c/cae7cab804c943d723d52724a3aeb07a3f4a2650 https://git.kernel.org/linus/902c0b1887522a099aa4e1e6b4b476c2fe5dd13e

JSON

To clipboard

{
  "CVSS 2.0": "AV:L/AC:L/Au:S/C:N/I:N/A:C",
  "CVSS 3.0": "AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H",
  "CVSS 4.0": null,
  "remediation_\u0418\u0434\u0435\u043d\u0442\u0438\u0444\u0438\u043a\u0430\u0442\u043e\u0440": null,
  "remediation_\u041d\u0430\u0438\u043c\u0435\u043d\u043e\u0432\u0430\u043d\u0438\u0435": null,
  "\u0412\u0435\u043d\u0434\u043e\u0440 \u041f\u041e": "\u0421\u043e\u043e\u0431\u0449\u0435\u0441\u0442\u0432\u043e \u0441\u0432\u043e\u0431\u043e\u0434\u043d\u043e\u0433\u043e \u043f\u0440\u043e\u0433\u0440\u0430\u043c\u043c\u043d\u043e\u0433\u043e \u043e\u0431\u0435\u0441\u043f\u0435\u0447\u0435\u043d\u0438\u044f",
  "\u0412\u0435\u0440\u0441\u0438\u044f \u041f\u041e": "\u043e\u0442 5.11 \u0434\u043e 5.14.14 \u0432\u043a\u043b\u044e\u0447\u0438\u0442\u0435\u043b\u044c\u043d\u043e (Linux), \u043e\u0442 5.7 \u0434\u043e 5.10.75 \u0432\u043a\u043b\u044e\u0447\u0438\u0442\u0435\u043b\u044c\u043d\u043e (Linux)",
  "\u0412\u043e\u0437\u043c\u043e\u0436\u043d\u044b\u0435 \u043c\u0435\u0440\u044b \u043f\u043e \u0443\u0441\u0442\u0440\u0430\u043d\u0435\u043d\u0438\u044e": "\u0412 \u0443\u0441\u043b\u043e\u0432\u0438\u044f\u0445 \u043e\u0442\u0441\u0443\u0442\u0441\u0442\u0432\u0438\u044f \u043e\u0431\u043d\u043e\u0432\u043b\u0435\u043d\u0438\u0439 \u0431\u0435\u0437\u043e\u043f\u0430\u0441\u043d\u043e\u0441\u0442\u0438 \u043e\u0442 \u043f\u0440\u043e\u0438\u0437\u0432\u043e\u0434\u0438\u0442\u0435\u043b\u044f \u0440\u0435\u043a\u043e\u043c\u0435\u043d\u0434\u0443\u0435\u0442\u0441\u044f \u043f\u0440\u0438\u0434\u0435\u0440\u0436\u0438\u0432\u0430\u0442\u044c\u0441\u044f \"\u0420\u0435\u043a\u043e\u043c\u0435\u043d\u0434\u0430\u0446\u0438\u0439 \u043f\u043e \u0431\u0435\u0437\u043e\u043f\u0430\u0441\u043d\u043e\u0439 \u043d\u0430\u0441\u0442\u0440\u043e\u0439\u043a\u0435 \u043e\u043f\u0435\u0440\u0430\u0446\u0438\u043e\u043d\u043d\u044b\u0445 \u0441\u0438\u0441\u0442\u0435\u043c LINUX\", \u0438\u0437\u043b\u043e\u0436\u0435\u043d\u043d\u044b\u0445 \u0432 \u043c\u0435\u0442\u043e\u0434\u0438\u0447\u0435\u0441\u043a\u043e\u043c \u0434\u043e\u043a\u0443\u043c\u0435\u043d\u0442\u0435 \u0424\u0421\u0422\u042d\u041a \u0420\u043e\u0441\u0441\u0438\u0438, \u0443\u0442\u0432\u0435\u0440\u0436\u0434\u0451\u043d\u043d\u043e\u043c 25 \u0434\u0435\u043a\u0430\u0431\u0440\u044f 2022 \u0433\u043e\u0434\u0430.\n\n\n\n\u0418\u0441\u043f\u043e\u043b\u044c\u0437\u043e\u0432\u0430\u043d\u0438\u0435 \u0440\u0435\u043a\u043e\u043c\u0435\u043d\u0434\u0430\u0446\u0438\u0439:\n\n\u0414\u043b\u044f Linux:\nhttps://git.kernel.org/stable/c/2a670c323055282c9b72794a491d53cef86bbeaf\nhttps://git.kernel.org/stable/c/cae7cab804c943d723d52724a3aeb07a3f4a2650\nhttps://git.kernel.org/linus/902c0b1887522a099aa4e1e6b4b476c2fe5dd13e",
  "\u0414\u0430\u0442\u0430 \u0432\u044b\u044f\u0432\u043b\u0435\u043d\u0438\u044f": "04.10.2021",
  "\u0414\u0430\u0442\u0430 \u043f\u043e\u0441\u043b\u0435\u0434\u043d\u0435\u0433\u043e \u043e\u0431\u043d\u043e\u0432\u043b\u0435\u043d\u0438\u044f": "16.11.2025",
  "\u0414\u0430\u0442\u0430 \u043f\u0443\u0431\u043b\u0438\u043a\u0430\u0446\u0438\u0438": "16.11.2025",
  "\u0418\u0434\u0435\u043d\u0442\u0438\u0444\u0438\u043a\u0430\u0442\u043e\u0440": "BDU:2025-14236",
  "\u0418\u0434\u0435\u043d\u0442\u0438\u0444\u0438\u043a\u0430\u0442\u043e\u0440\u044b \u0434\u0440\u0443\u0433\u0438\u0445 \u0441\u0438\u0441\u0442\u0435\u043c \u043e\u043f\u0438\u0441\u0430\u043d\u0438\u0439 \u0443\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u0438": "CVE-2021-47451",
  "\u0418\u043d\u0444\u043e\u0440\u043c\u0430\u0446\u0438\u044f \u043e\u0431 \u0443\u0441\u0442\u0440\u0430\u043d\u0435\u043d\u0438\u0438": "\u0423\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u044c \u0443\u0441\u0442\u0440\u0430\u043d\u0435\u043d\u0430",
  "\u041a\u043b\u0430\u0441\u0441 \u0443\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u0438": "\u0423\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u044c \u043a\u043e\u0434\u0430",
  "\u041d\u0430\u0437\u0432\u0430\u043d\u0438\u0435 \u041f\u041e": "Linux",
  "\u041d\u0430\u0438\u043c\u0435\u043d\u043e\u0432\u0430\u043d\u0438\u0435 \u041e\u0421 \u0438 \u0442\u0438\u043f \u0430\u043f\u043f\u0430\u0440\u0430\u0442\u043d\u043e\u0439 \u043f\u043b\u0430\u0442\u0444\u043e\u0440\u043c\u044b": "\u0421\u043e\u043e\u0431\u0449\u0435\u0441\u0442\u0432\u043e \u0441\u0432\u043e\u0431\u043e\u0434\u043d\u043e\u0433\u043e \u043f\u0440\u043e\u0433\u0440\u0430\u043c\u043c\u043d\u043e\u0433\u043e \u043e\u0431\u0435\u0441\u043f\u0435\u0447\u0435\u043d\u0438\u044f Linux \u043e\u0442 5.11 \u0434\u043e 5.14.14 \u0432\u043a\u043b\u044e\u0447\u0438\u0442\u0435\u043b\u044c\u043d\u043e , \u0421\u043e\u043e\u0431\u0449\u0435\u0441\u0442\u0432\u043e \u0441\u0432\u043e\u0431\u043e\u0434\u043d\u043e\u0433\u043e \u043f\u0440\u043e\u0433\u0440\u0430\u043c\u043c\u043d\u043e\u0433\u043e \u043e\u0431\u0435\u0441\u043f\u0435\u0447\u0435\u043d\u0438\u044f Linux \u043e\u0442 5.7 \u0434\u043e 5.10.75 \u0432\u043a\u043b\u044e\u0447\u0438\u0442\u0435\u043b\u044c\u043d\u043e ",
  "\u041d\u0430\u0438\u043c\u0435\u043d\u043e\u0432\u0430\u043d\u0438\u0435 \u0443\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u0438": "\u0423\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u044c \u0444\u0443\u043d\u043a\u0446\u0438\u0438 idletimer_tg_create() \u043c\u043e\u0434\u0443\u043b\u044f net/netfilter/xt_IDLETIMER.c \u043a\u043e\u043c\u043f\u043e\u043d\u0435\u043d\u0442\u0430 netfilter \u044f\u0434\u0440\u0430 \u043e\u043f\u0435\u0440\u0430\u0446\u0438\u043e\u043d\u043d\u043e\u0439 \u0441\u0438\u0441\u0442\u0435\u043c\u044b Linux, \u043f\u043e\u0437\u0432\u043e\u043b\u044f\u044e\u0449\u0430\u044f \u043d\u0430\u0440\u0443\u0448\u0438\u0442\u0435\u043b\u044e \u0432\u044b\u0437\u0432\u0430\u0442\u044c \u043e\u0442\u043a\u0430\u0437 \u0432 \u043e\u0431\u0441\u043b\u0443\u0436\u0438\u0432\u0430\u043d\u0438\u0438",
  "\u041d\u0430\u043b\u0438\u0447\u0438\u0435 \u044d\u043a\u0441\u043f\u043b\u043e\u0439\u0442\u0430": "\u0414\u0430\u043d\u043d\u044b\u0435 \u0443\u0442\u043e\u0447\u043d\u044f\u044e\u0442\u0441\u044f",
  "\u041e\u043f\u0438\u0441\u0430\u043d\u0438\u0435 \u043e\u0448\u0438\u0431\u043a\u0438 CWE": "\u0418\u0441\u043f\u043e\u043b\u044c\u0437\u043e\u0432\u0430\u043d\u0438\u0435 \u043d\u0435\u0438\u043d\u0438\u0446\u0438\u0430\u043b\u0438\u0437\u0438\u0440\u043e\u0432\u0430\u043d\u043d\u043e\u0439 \u043f\u0435\u0440\u0435\u043c\u0435\u043d\u043d\u043e\u0439 (CWE-457), \u0418\u0441\u043f\u043e\u043b\u044c\u0437\u043e\u0432\u0430\u043d\u0438\u0435 \u043d\u0435\u0438\u043d\u0438\u0446\u0438\u0430\u043b\u0438\u0437\u0438\u0440\u043e\u0432\u0430\u043d\u043d\u043e\u0433\u043e \u0440\u0435\u0441\u0443\u0440\u0441\u0430 (CWE-908)",
  "\u041e\u043f\u0438\u0441\u0430\u043d\u0438\u0435 \u0443\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u0438": "\u0423\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u044c \u0444\u0443\u043d\u043a\u0446\u0438\u0438 idletimer_tg_create() \u043c\u043e\u0434\u0443\u043b\u044f net/netfilter/xt_IDLETIMER.c \u043a\u043e\u043c\u043f\u043e\u043d\u0435\u043d\u0442\u0430 netfilter \u044f\u0434\u0440\u0430 \u043e\u043f\u0435\u0440\u0430\u0446\u0438\u043e\u043d\u043d\u043e\u0439 \u0441\u0438\u0441\u0442\u0435\u043c\u044b Linux \u0441\u0432\u044f\u0437\u0430\u043d\u0430 \u0441 \u0438\u0441\u043f\u043e\u043b\u044c\u0437\u043e\u0432\u0430\u043d\u0438\u0435\u043c \u043d\u0435\u0438\u043d\u0438\u0446\u0438\u0430\u043b\u0438\u0437\u0438\u0440\u043e\u0432\u0430\u043d\u043d\u044b\u0445 \u043f\u0435\u0440\u0435\u043c\u0435\u043d\u043d\u044b\u0445. \u042d\u043a\u0441\u043f\u043b\u0443\u0430\u0442\u0430\u0446\u0438\u044f \u0443\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u0438 \u043c\u043e\u0436\u0435\u0442 \u043f\u043e\u0437\u0432\u043e\u043b\u0438\u0442\u044c \u043d\u0430\u0440\u0443\u0448\u0438\u0442\u0435\u043b\u044e \u0432\u044b\u0437\u0432\u0430\u0442\u044c \u043e\u0442\u043a\u0430\u0437 \u0432 \u043e\u0431\u0441\u043b\u0443\u0436\u0438\u0432\u0430\u043d\u0438\u0438",
  "\u041f\u043e\u0441\u043b\u0435\u0434\u0441\u0442\u0432\u0438\u044f \u044d\u043a\u0441\u043f\u043b\u0443\u0430\u0442\u0430\u0446\u0438\u0438 \u0443\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u0438": null,
  "\u041f\u0440\u043e\u0447\u0430\u044f \u0438\u043d\u0444\u043e\u0440\u043c\u0430\u0446\u0438\u044f": null,
  "\u0421\u0432\u044f\u0437\u044c \u0441 \u0438\u043d\u0446\u0438\u0434\u0435\u043d\u0442\u0430\u043c\u0438 \u0418\u0411": "\u0414\u0430\u043d\u043d\u044b\u0435 \u0443\u0442\u043e\u0447\u043d\u044f\u044e\u0442\u0441\u044f",
  "\u0421\u043e\u0441\u0442\u043e\u044f\u043d\u0438\u0435 \u0443\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u0438": "\u041e\u043f\u0443\u0431\u043b\u0438\u043a\u043e\u0432\u0430\u043d\u0430",
  "\u0421\u043f\u043e\u0441\u043e\u0431 \u0443\u0441\u0442\u0440\u0430\u043d\u0435\u043d\u0438\u044f": "\u041e\u0431\u043d\u043e\u0432\u043b\u0435\u043d\u0438\u0435 \u043f\u0440\u043e\u0433\u0440\u0430\u043c\u043c\u043d\u043e\u0433\u043e \u043e\u0431\u0435\u0441\u043f\u0435\u0447\u0435\u043d\u0438\u044f",
  "\u0421\u043f\u043e\u0441\u043e\u0431 \u044d\u043a\u0441\u043f\u043b\u0443\u0430\u0442\u0430\u0446\u0438\u0438": "\u041c\u0430\u043d\u0438\u043f\u0443\u043b\u0438\u0440\u043e\u0432\u0430\u043d\u0438\u0435 \u0441\u0442\u0440\u0443\u043a\u0442\u0443\u0440\u0430\u043c\u0438 \u0434\u0430\u043d\u043d\u044b\u0445, \u041c\u0430\u043d\u0438\u043f\u0443\u043b\u0438\u0440\u043e\u0432\u0430\u043d\u0438\u0435 \u0440\u0435\u0441\u0443\u0440\u0441\u0430\u043c\u0438",
  "\u0421\u0441\u044b\u043b\u043a\u0438 \u043d\u0430 \u0438\u0441\u0442\u043e\u0447\u043d\u0438\u043a\u0438": "https://www.cve.org/CVERecord?id=CVE-2021-47451\nhttps://git.kernel.org/stable/c/2a670c323055282c9b72794a491d53cef86bbeaf\nhttps://git.kernel.org/stable/c/cae7cab804c943d723d52724a3aeb07a3f4a2650\nhttps://lore.kernel.org/linux-cve-announce/2024052242-CVE-2021-47451-72c7@gregkh/\nhttps://git.kernel.org/linus/902c0b1887522a099aa4e1e6b4b476c2fe5dd13e\nhttps://git.linuxtesting.ru/pub/scm/linux/kernel/git/lvc/linux-stable.git/commit/?h=v5.10.176-lvc1\u0026id=2a670c323055282c9b72794a491d53cef86bbeaf\nhttps://kernel.org/pub/linux/kernel/v5.x/ChangeLog-5.10.76\nhttps://kernel.org/pub/linux/kernel/v5.x/ChangeLog-5.14.15",
  "\u0421\u0442\u0430\u0442\u0443\u0441 \u0443\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u0438": "\u041f\u043e\u0434\u0442\u0432\u0435\u0440\u0436\u0434\u0435\u043d\u0430 \u043f\u0440\u043e\u0438\u0437\u0432\u043e\u0434\u0438\u0442\u0435\u043b\u0435\u043c",
  "\u0422\u0438\u043f \u041f\u041e": "\u041e\u043f\u0435\u0440\u0430\u0446\u0438\u043e\u043d\u043d\u0430\u044f \u0441\u0438\u0441\u0442\u0435\u043c\u0430",
  "\u0422\u0438\u043f \u043e\u0448\u0438\u0431\u043a\u0438 CWE": "CWE-457, CWE-908",
  "\u0423\u0440\u043e\u0432\u0435\u043d\u044c \u043e\u043f\u0430\u0441\u043d\u043e\u0441\u0442\u0438 \u0443\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u0438": "\u0421\u0440\u0435\u0434\u043d\u0438\u0439 \u0443\u0440\u043e\u0432\u0435\u043d\u044c \u043e\u043f\u0430\u0441\u043d\u043e\u0441\u0442\u0438 (\u0431\u0430\u0437\u043e\u0432\u0430\u044f \u043e\u0446\u0435\u043d\u043a\u0430 CVSS 2.0 \u0441\u043e\u0441\u0442\u0430\u0432\u043b\u044f\u0435\u0442 4,6)\n\u0421\u0440\u0435\u0434\u043d\u0438\u0439 \u0443\u0440\u043e\u0432\u0435\u043d\u044c \u043e\u043f\u0430\u0441\u043d\u043e\u0441\u0442\u0438 (\u0431\u0430\u0437\u043e\u0432\u0430\u044f \u043e\u0446\u0435\u043d\u043a\u0430 CVSS 3.1 \u0441\u043e\u0441\u0442\u0430\u0432\u043b\u044f\u0435\u0442 5,5)"
}

CVE-2021-47451 (GCVE-0-2021-47451)

Vulnerability from cvelistv5 – Published: 2024-05-22 06:19 – Updated: 2026-08-05 08:47

Title

netfilter: xt_IDLETIMER: fix panic that occurs when timer_type has garbage value

Summary

In the Linux kernel, the following vulnerability has been resolved: netfilter: xt_IDLETIMER: fix panic that occurs when timer_type has garbage value Currently, when the rule related to IDLETIMER is added, idletimer_tg timer structure is initialized by kmalloc on executing idletimer_tg_create function. However, in this process timer->timer_type is not defined to a specific value. Thus, timer->timer_type has garbage value and it occurs kernel panic. So, this commit fixes the panic by initializing timer->timer_type using kzalloc instead of kmalloc. Test commands: # iptables -A OUTPUT -j IDLETIMER --timeout 1 --label test $ cat /sys/class/xt_idletimer/timers/test Killed Splat looks like: BUG: KASAN: user-memory-access in alarm_expires_remaining+0x49/0x70 Read of size 8 at addr 0000002e8c7bc4c8 by task cat/917 CPU: 12 PID: 917 Comm: cat Not tainted 5.14.0+ #3 79940a339f71eb14fc81aee1757a20d5bf13eb0e Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.13.0-1ubuntu1.1 04/01/2014 Call Trace: dump_stack_lvl+0x6e/0x9c kasan_report.cold+0x112/0x117 ? alarm_expires_remaining+0x49/0x70 __asan_load8+0x86/0xb0 alarm_expires_remaining+0x49/0x70 idletimer_tg_show+0xe5/0x19b [xt_IDLETIMER 11219304af9316a21bee5ba9d58f76a6b9bccc6d] dev_attr_show+0x3c/0x60 sysfs_kf_seq_show+0x11d/0x1f0 ? device_remove_bin_file+0x20/0x20 kernfs_seq_show+0xa4/0xb0 seq_read_iter+0x29c/0x750 kernfs_fop_read_iter+0x25a/0x2c0 ? __fsnotify_parent+0x3d1/0x570 ? iov_iter_init+0x70/0x90 new_sync_read+0x2a7/0x3d0 ? __x64_sys_llseek+0x230/0x230 ? rw_verify_area+0x81/0x150 vfs_read+0x17b/0x240 ksys_read+0xd9/0x180 ? vfs_write+0x460/0x460 ? do_syscall_64+0x16/0xc0 ? lockdep_hardirqs_on+0x79/0x120 __x64_sys_read+0x43/0x50 do_syscall_64+0x3b/0xc0 entry_SYSCALL_64_after_hwframe+0x44/0xae RIP: 0033:0x7f0cdc819142 Code: c0 e9 c2 fe ff ff 50 48 8d 3d 3a ca 0a 00 e8 f5 19 02 00 0f 1f 44 00 00 f3 0f 1e fa 64 8b 04 25 18 00 00 00 85 c0 75 10 0f 05 <48> 3d 00 f0 ff ff 77 56 c3 0f 1f 44 00 00 48 83 ec 28 48 89 54 24 RSP: 002b:00007fff28eee5b8 EFLAGS: 00000246 ORIG_RAX: 0000000000000000 RAX: ffffffffffffffda RBX: 0000000000020000 RCX: 00007f0cdc819142 RDX: 0000000000020000 RSI: 00007f0cdc032000 RDI: 0000000000000003 RBP: 00007f0cdc032000 R08: 00007f0cdc031010 R09: 0000000000000000 R10: 0000000000000022 R11: 0000000000000246 R12: 00005607e9ee31f0 R13: 0000000000000003 R14: 0000000000020000 R15: 0000000000020000

Severity

7.8 (High)


                        
                          CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

SSVC

Exploitation: none Automatable: no Technical Impact: partial

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2024-05-24 19:25 UTC

Assigner

Linux mitre root

References

3 references

URL	Tags
https://git.kernel.org/stable/c/2a670c323055282c9…
https://git.kernel.org/stable/c/cae7cab804c943d72…
https://git.kernel.org/stable/c/902c0b1887522a099…

Impacted products

2 products

Vendor	Product	Version
Linux	Linux	Affected: 68983a354a655c35d3fb204489d383a2a051fda7 , < 2a670c323055282c9b72794a491d53cef86bbeaf (git) Affected: 68983a354a655c35d3fb204489d383a2a051fda7 , < cae7cab804c943d723d52724a3aeb07a3f4a2650 (git) Affected: 68983a354a655c35d3fb204489d383a2a051fda7 , < 902c0b1887522a099aa4e1e6b4b476c2fe5dd13e (git)
Linux	Linux	Affected: 5.7 Unaffected: 0 , < 5.7 (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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{
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                "id": "CVE-2021-47451",
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                "role": "CISA Coordinator",
                "timestamp": "2024-05-24T19:25:32.208577Z",
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            {
              "lang": "en",
              "value": "AV:L - The bug is reached by adding an xt_IDLETIMER iptables/ip6tables rule (setsockopt/netlink) and then reading the world-readable sysfs attribute under /sys/class/xt_idletimer/timers/; per guidance netfilter/xtables is Local, not Network.\nAC:L - An attacker who can create the rule and read the sysfs file triggers the path reliably; roughly half of uninitialized timer_type values take the alarm branch, and retries or heap spraying make favorable garbage deterministic with no victim-controlled precondition.\nPR:L - Creating IDLETIMER rules only needs CAP_NET_ADMIN checked via ns_capable() in do_ipt_set_ctl/do_ip6t_set_ctl, which an unprivileged user obtains in a user+net namespace; alternatively, if a rule already exists (common on Android), any unprivileged process can trigger via the 0444 sysfs show path.\nUI:N - The attacker creates the IDLETIMER target and reads the sysfs timer attribute themselves; no separate victim action is required.\nS:U - Impact is confined to the host kernel authority (oops/panic or local privilege-escalation class memory unsafety); this is not a VM escape, IOMMU bypass, or other cross-boundary compromise.\nC:H - idletimer_tg_show calls alarm_expires_remaining() on an uninitialized struct alarm, using garbage alarm-\u003etype as an unbounded index into alarm_bases[] (OOB read of kernel memory) and returning derived values to userspace via sysfs; per guidance unbounded OOB reads score Confidentiality High.\nI:H - The same OOB alarm_bases[type] access loads and invokes base-\u003eget_ktime() as a function pointer from attacker-influenced/out-of-bounds memory, which is a control-flow hijack primitive; with heap spraying of the kmalloc\u0027d idletimer_tg this is Integrity High.\nA:H - The demonstrated KASAN user-memory-access in alarm_expires_remaining leads to kernel oops/panic when the uninitialized alarm path is taken, fully denying availability."
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      "title": "netfilter: xt_IDLETIMER: fix panic that occurs when timer_type has garbage value",
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        "engine": "bippy-1.2.0"
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    "cveId": "CVE-2021-47451",
    "datePublished": "2024-05-22T06:19:42.082Z",
    "dateReserved": "2024-05-21T14:58:30.832Z",
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}

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.

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.
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BDU:2025-14236 (CVE-2021-47451)

CVE-2021-47451 (GCVE-0-2021-47451)

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Nomenclature

Related by attack behaviour