CVE-2021-21781: Medium severity Linux Linux kernel vulnerability

Published Jun 25, 2021
·
Updated

An information disclosure flaw exists in the ARM SIGPAGE functionality of the Linux kernel. An attacker with a local account can read the contents of the sigpage, which contains previously initialized kernel memory contents. This flaw requires an attacker to read a process’s memory at a specific offset to trigger this vulnerability.

Other sources

An information disclosure vulnerability exists in the ARM SIGPAGE functionality of Linux Kernel v5.4.66 and v5.4.54. The latest version (5.11-rc4) seems to still be vulnerable. A userland application can read the contents of the sigpage, which can leak kernel memory contents. An attacker can read a process’s memory at a specific offset to trigger this vulnerability. This was fixed in kernel releases: 4.14.222 4.19.177 5.4.99 5.10.17 5.11

An information disclosure vulnerability exists in the ARM SIGPAGE functionality of Linux Kernel. A userland application can read the contents of the sigpage (A page in which signal handler information is stored), which can leak kernel memory contents. A local attacker can read a process’s memory at a specific offset to read this information leak.

Reference: https://talosintelligence.com/vulnerabilityreports/TALOS-2021-1243

— Red Hat

In getsignalpage of signal.c, there is a possible leak of kernel data due to uninitialized data. This could lead to local information disclosure with no additional execution privileges needed. User interaction is not needed for exploitation.

— OSV

Affected Software

84 affected componentsFixes available
redhat/kernel<0:4.18.0-372.9.1.el8
0:4.18.0-372.9.1.el8
Linux Linux kernel=5.4.54
Linux Linux kernel=5.4.66
Oracle Communications Cloud Native Core Binding Support Function=22.1.3
Oracle Communications Cloud Native Core Network Exposure Function=22.1.1
Oracle Communications Cloud Native Core Policy=22.2.0
android/:linux_kernel:>=:0<:2022-03-05
:2022-03-05
ubuntu/linux-azure<4.15.0-1114.127~14.04.1
4.15.0-1114.127~14.04.1
ubuntu/linux*
ubuntu/linux-aws*
ubuntu/linux-lts-xenial*
ubuntu/linux-aws-hwe<4.15.0-1102.109~16.04.1
4.15.0-1102.109~16.04.1
ubuntu/linux-azure<4.15.0-1114.127~16.04.1
4.15.0-1114.127~16.04.1
ubuntu/linux-gcp<4.15.0-1099.112~16.04.1
4.15.0-1099.112~16.04.1
ubuntu/linux-hwe<4.15.0-143.147~16.04.3
4.15.0-143.147~16.04.3
ubuntu/linux-oracle<4.15.0-1071.79~16.04.1
4.15.0-1071.79~16.04.1
ubuntu/linux*
ubuntu/linux-aws*
ubuntu/linux-hwe-edge*
ubuntu/linux-kvm*
ubuntu/linux-fips*
ubuntu/linux-fips*
ubuntu/linux<4.15.0-143.147
4.15.0-143.147
ubuntu/linux-aws<4.15.0-1102.109
4.15.0-1102.109
ubuntu/linux-aws-5.4<5.4.0-1043.45~18.04.1
5.4.0-1043.45~18.04.1
ubuntu/linux-azure-4.15<4.15.0-1114.127
4.15.0-1114.127
ubuntu/linux-azure-5.4<5.4.0-1044.46~18.04.1
5.4.0-1044.46~18.04.1
ubuntu/linux-dell300x<4.15.0-1018.22
4.15.0-1018.22
ubuntu/linux-gcp-4.15<4.15.0-1099.112
4.15.0-1099.112
ubuntu/linux-gcp-5.4<5.4.0-1041.44~18.04.1
5.4.0-1041.44~18.04.1
ubuntu/linux-gke-5.4<5.4.0-1040.42~18.04.1
5.4.0-1040.42~18.04.1
ubuntu/linux-gkeop-5.4<5.4.0-1013.14~18.04.1
5.4.0-1013.14~18.04.1
ubuntu/linux-hwe-5.4<5.4.0-71.79~18.04.1
5.4.0-71.79~18.04.1
ubuntu/linux-kvm<4.15.0-1091.93
4.15.0-1091.93
ubuntu/linux-oracle<4.15.0-1071.79
4.15.0-1071.79
ubuntu/linux-oracle-5.4<5.4.0-1042.45~18.04.1
5.4.0-1042.45~18.04.1
ubuntu/linux-raspi-5.4<5.4.0-1033.36~18.04.1
5.4.0-1033.36~18.04.1
ubuntu/linux-raspi2<4.15.0-1085.90
4.15.0-1085.90
ubuntu/linux-snapdragon<4.15.0-1102.111
4.15.0-1102.111
ubuntu/linux-aws-5.0*
ubuntu/linux-aws-5.3*
ubuntu/linux-azure*
ubuntu/linux-azure-5.3*
ubuntu/linux-azure-edge*
ubuntu/linux-gcp*
ubuntu/linux-gcp-5.3*
ubuntu/linux-gcp-edge*
ubuntu/linux-gke-4.15*
ubuntu/linux-hwe*
ubuntu/linux-hwe-edge*
ubuntu/linux-oem*
ubuntu/linux-oracle-5.0*
ubuntu/linux-oracle-5.3*
ubuntu/linux-aws-fips<4.15.0-2044.46
4.15.0-2044.46
ubuntu/linux-azure-fips<4.15.0-2026.29
4.15.0-2026.29
ubuntu/linux-fips<4.15.0-1059.67
4.15.0-1059.67
ubuntu/linux-aws-fips*
ubuntu/linux-azure-fips*
ubuntu/linux-fips*
ubuntu/linux-gcp-fips*
ubuntu/linux<5.4.0-71.79
5.4.0-71.79
ubuntu/linux-aws<5.4.0-1043.45
5.4.0-1043.45
ubuntu/linux-azure<5.4.0-1044.46
5.4.0-1044.46
ubuntu/linux-gcp<5.4.0-1041.44
5.4.0-1041.44
ubuntu/linux-gke<5.4.0-1041.43
5.4.0-1041.43
ubuntu/linux-gkeop<5.4.0-1013.14
5.4.0-1013.14
ubuntu/linux-hwe-5.8<5.8.0-53.60~20.04.1
5.8.0-53.60~20.04.1
ubuntu/linux-kvm<5.4.0-1037.38
5.4.0-1037.38
ubuntu/linux-oem-5.10<5.10.0-1017.18
5.10.0-1017.18
ubuntu/linux-oracle<5.4.0-1042.45
5.4.0-1042.45
ubuntu/linux-raspi<5.4.0-1033.36
5.4.0-1033.36
ubuntu/linux-riscv-5.8<5.8.0-25.27~20.04.1
5.8.0-25.27~20.04.1
ubuntu/linux-oem-5.6*
ubuntu/linux-raspi2*
ubuntu/linux-riscv*
ubuntu/linux-aws-fips<5.4.0-1069.73+fips2
5.4.0-1069.73+fips2
ubuntu/linux-azure-fips<5.4.0-1073.76+fips1
5.4.0-1073.76+fips1
ubuntu/linux-gcp-fips<5.4.0-1067.71~20.04.1
5.4.0-1067.71~20.04.1
ubuntu/linux-aws-fips*
ubuntu/linux-azure-fips*
ubuntu/linux-gcp-fips*
ubuntu/linux-intel-iot-realtime*
ubuntu/linux-realtime*
ubuntu/linux-raspi-realtime*

Remediation

Recommended actions to resolve this vulnerability, in priority order.

  1. Upgrade

    Upgrade redhat/kernel to a version that resolves this vulnerability.

    Fixed in 0:4.18.0-372.9.1.el8
  2. Upgrade

    Upgrade android/:linux_kernel: to a version that resolves this vulnerability.

    Fixed in :2022-03-05
  3. Upgrade

    Upgrade ubuntu/linux-azure to a version that resolves this vulnerability.

    Fixed in 4.15.0-1114.127~14.04.1
  4. Upgrade

    Upgrade ubuntu/linux-aws-hwe to a version that resolves this vulnerability.

    Fixed in 4.15.0-1102.109~16.04.1
  5. Upgrade

    Upgrade ubuntu/linux-azure to a version that resolves this vulnerability.

    Fixed in 4.15.0-1114.127~16.04.1
  6. Upgrade

    Upgrade ubuntu/linux-gcp to a version that resolves this vulnerability.

    Fixed in 4.15.0-1099.112~16.04.1
  7. Upgrade

    Upgrade ubuntu/linux-hwe to a version that resolves this vulnerability.

    Fixed in 4.15.0-143.147~16.04.3
  8. Upgrade

    Upgrade ubuntu/linux-oracle to a version that resolves this vulnerability.

    Fixed in 4.15.0-1071.79~16.04.1
  9. Upgrade

    Upgrade ubuntu/linux to a version that resolves this vulnerability.

    Fixed in 4.15.0-143.147
  10. Upgrade

    Upgrade ubuntu/linux-aws to a version that resolves this vulnerability.

    Fixed in 4.15.0-1102.109
  11. Upgrade

    Upgrade ubuntu/linux-aws-5.4 to a version that resolves this vulnerability.

    Fixed in 5.4.0-1043.45~18.04.1
  12. Upgrade

    Upgrade ubuntu/linux-azure-4.15 to a version that resolves this vulnerability.

    Fixed in 4.15.0-1114.127
  13. Upgrade

    Upgrade ubuntu/linux-azure-5.4 to a version that resolves this vulnerability.

    Fixed in 5.4.0-1044.46~18.04.1
  14. Upgrade

    Upgrade ubuntu/linux-dell300x to a version that resolves this vulnerability.

    Fixed in 4.15.0-1018.22
  15. Upgrade

    Upgrade ubuntu/linux-gcp-4.15 to a version that resolves this vulnerability.

    Fixed in 4.15.0-1099.112
  16. Upgrade

    Upgrade ubuntu/linux-gcp-5.4 to a version that resolves this vulnerability.

    Fixed in 5.4.0-1041.44~18.04.1
  17. Upgrade

    Upgrade ubuntu/linux-gke-5.4 to a version that resolves this vulnerability.

    Fixed in 5.4.0-1040.42~18.04.1
  18. Upgrade

    Upgrade ubuntu/linux-gkeop-5.4 to a version that resolves this vulnerability.

    Fixed in 5.4.0-1013.14~18.04.1
  19. Upgrade

    Upgrade ubuntu/linux-hwe-5.4 to a version that resolves this vulnerability.

    Fixed in 5.4.0-71.79~18.04.1
  20. Upgrade

    Upgrade ubuntu/linux-kvm to a version that resolves this vulnerability.

    Fixed in 4.15.0-1091.93
  21. Upgrade

    Upgrade ubuntu/linux-oracle to a version that resolves this vulnerability.

    Fixed in 4.15.0-1071.79
  22. Upgrade

    Upgrade ubuntu/linux-oracle-5.4 to a version that resolves this vulnerability.

    Fixed in 5.4.0-1042.45~18.04.1
  23. Upgrade

    Upgrade ubuntu/linux-raspi-5.4 to a version that resolves this vulnerability.

    Fixed in 5.4.0-1033.36~18.04.1
  24. Upgrade

    Upgrade ubuntu/linux-raspi2 to a version that resolves this vulnerability.

    Fixed in 4.15.0-1085.90
  25. Upgrade

    Upgrade ubuntu/linux-snapdragon to a version that resolves this vulnerability.

    Fixed in 4.15.0-1102.111
  26. Upgrade

    Upgrade ubuntu/linux-aws-fips to a version that resolves this vulnerability.

    Fixed in 4.15.0-2044.46
  27. Upgrade

    Upgrade ubuntu/linux-azure-fips to a version that resolves this vulnerability.

    Fixed in 4.15.0-2026.29
  28. Upgrade

    Upgrade ubuntu/linux-fips to a version that resolves this vulnerability.

    Fixed in 4.15.0-1059.67
  29. Upgrade

    Upgrade ubuntu/linux to a version that resolves this vulnerability.

    Fixed in 5.4.0-71.79
  30. Upgrade

    Upgrade ubuntu/linux-aws to a version that resolves this vulnerability.

    Fixed in 5.4.0-1043.45
  31. Upgrade

    Upgrade ubuntu/linux-azure to a version that resolves this vulnerability.

    Fixed in 5.4.0-1044.46
  32. Upgrade

    Upgrade ubuntu/linux-gcp to a version that resolves this vulnerability.

    Fixed in 5.4.0-1041.44
  33. Upgrade

    Upgrade ubuntu/linux-gke to a version that resolves this vulnerability.

    Fixed in 5.4.0-1041.43
  34. Upgrade

    Upgrade ubuntu/linux-gkeop to a version that resolves this vulnerability.

    Fixed in 5.4.0-1013.14
  35. Upgrade

    Upgrade ubuntu/linux-hwe-5.8 to a version that resolves this vulnerability.

    Fixed in 5.8.0-53.60~20.04.1
  36. Upgrade

    Upgrade ubuntu/linux-kvm to a version that resolves this vulnerability.

    Fixed in 5.4.0-1037.38
  37. Upgrade

    Upgrade ubuntu/linux-oem-5.10 to a version that resolves this vulnerability.

    Fixed in 5.10.0-1017.18
  38. Upgrade

    Upgrade ubuntu/linux-oracle to a version that resolves this vulnerability.

    Fixed in 5.4.0-1042.45
  39. Upgrade

    Upgrade ubuntu/linux-raspi to a version that resolves this vulnerability.

    Fixed in 5.4.0-1033.36
  40. Upgrade

    Upgrade ubuntu/linux-riscv-5.8 to a version that resolves this vulnerability.

    Fixed in 5.8.0-25.27~20.04.1
  41. Upgrade

    Upgrade ubuntu/linux-aws-fips to a version that resolves this vulnerability.

    Fixed in 5.4.0-1069.73+fips2
  42. Upgrade

    Upgrade ubuntu/linux-azure-fips to a version that resolves this vulnerability.

    Fixed in 5.4.0-1073.76+fips1
  43. Upgrade

    Upgrade ubuntu/linux-gcp-fips to a version that resolves this vulnerability.

    Fixed in 5.4.0-1067.71~20.04.1
  44. Upgrade

    Upgrade Linux kernel to a version that resolves this vulnerability.

    Fixed in 4.14.222
  45. Upgrade

    Upgrade Linux kernel to a version that resolves this vulnerability.

    Fixed in 4.19.177
  46. Upgrade

    Upgrade Linux kernel to a version that resolves this vulnerability.

    Fixed in 5.4.99
  47. Upgrade

    Upgrade Linux kernel to a version that resolves this vulnerability.

    Fixed in 5.10.17
  48. Upgrade

    Upgrade Linux kernel to a version that resolves this vulnerability.

    Fixed in 5.11

Event History

Jun 25, 2021
CVE Published
12:00 AM
Jul 13, 2021
Data Sourced
via Red Hat·07:01 PM
DescriptionSeverityAffected Software
Aug 18, 2021
CVE Published
via MITRE·02:37 PM
Data Sourced
via MITRE·02:37 PM
DescriptionSeverityWeakness
Data Sourced
via OSV·03:15 PM
DescriptionSeverityAffected Software
Mar 1, 2022
Advisory Published
via OSV·12:00 AM

Parent advisories

This vulnerability appears in the following advisories.

Frequently Asked Questions

1

What is CVE-2021-21781?

CVE-2021-21781 is an information disclosure vulnerability in the ARM SIGPAGE functionality of the Linux kernel.

2

What is the severity of CVE-2021-21781?

CVE-2021-21781 has a severity level of medium (4 out of 10).

3

Which versions of the Linux kernel are affected by CVE-2021-21781?

CVE-2021-21781 affects Linux Kernel versions 5.4.66 and 5.4.54.

4

How can an attacker exploit CVE-2021-21781?

An attacker can exploit CVE-2021-21781 by using a userland application to read the contents of the sigpage, which can leak kernel memory contents.

5

Are there any fixes or patches available for CVE-2021-21781?

Yes, there are fixes available for CVE-2021-21781. Please refer to the references for more information.

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