CVE-2021-29155: Medium severity Linux Linux kernel vulnerability

Published Apr 18, 2021
·
Updated

A vulnerability was discovered in retrieveptrlimit in kernel/bpf/verifier.c in the Linux kernel mechanism to mitigate speculatively out-of-bounds loads (Spectre mitigation). In this flaw a local, special user privileged (CAPSYSADMIN) BPF program running on affected systems may bypass the protection, and execute speculatively out-of-bounds loads from the kernel memory. This can be abused to extract contents of kernel memory via side-channel.

Other sources

A vulnerability was discovered in retrieveptrlimit in kernel/bpf/verifier.c in the Linux kernel mechanism to mitigate speculatively out-of-bounds loads (Spectre mitigation). In this flaw a local, special user privileged (CAPSYSADMIN) BPF programs running on affected systems can bypass the protection and execute speculatively out-of-bounds loads from the kernel memory. This can be abused to extract contents of kernel memory via side-channel.

Reference: https://www.openwall.com/lists/oss-security/2021/04/18/4

— Red Hat

An issue was discovered in the Linux kernel through 5.11.x. kernel/bpf/verifier.c performs undesirable out-of-bounds speculation on pointer arithmetic, leading to side-channel attacks that defeat Spectre mitigations and obtain sensitive information from kernel memory. Specifically, for sequences of pointer arithmetic operations, the pointer modification performed by the first operation is not correctly accounted for when restricting subsequent operations.

In several functions of verifier.c, there is a possible way to disclose kernel memory due to side channel information disclosure. This could lead to local information disclosure with System execution privileges needed. User interaction is not needed for exploitation.

— OSV

Affected Software

96 affected componentsFixes available
redhat/kernel-rt<0:4.18.0-348.rt7.130.el8
0:4.18.0-348.rt7.130.el8
redhat/kernel<0:4.18.0-348.el8
0:4.18.0-348.el8
redhat/kernel<5.12
5.12
Linux Linux kernel<5.11.16
Fedoraproject Fedora=32
Fedoraproject Fedora=33
Fedoraproject Fedora=34
Debian Debian Linux=9.0
debian/linux
5.10.223-15.10.234-16.1.129-16.1.135-16.12.25-16.12.27-1
android/:linux_kernel:>=:0<:2021-10-05
:2021-10-05
ubuntu/linux-azure<4.15.0-1121.134~14.04.1
4.15.0-1121.134~14.04.1
ubuntu/linux*
ubuntu/linux-aws*
ubuntu/linux-lts-xenial*
ubuntu/linux-aws-hwe<4.15.0-1109.116~16.04.1
4.15.0-1109.116~16.04.1
ubuntu/linux-azure<4.15.0-1121.134~16.04.1
4.15.0-1121.134~16.04.1
ubuntu/linux-gcp<4.15.0-1106.120~16.04.1
4.15.0-1106.120~16.04.1
ubuntu/linux-hwe<4.15.0-151.157~16.04.1
4.15.0-151.157~16.04.1
ubuntu/linux-oracle<4.15.0-1078.86~16.04.1
4.15.0-1078.86~16.04.1
ubuntu/linux*
ubuntu/linux-aws*
ubuntu/linux-hwe-edge*
ubuntu/linux-kvm*
ubuntu/linux-fips*
ubuntu/linux-fips*
ubuntu/linux<4.15.0-151.157
4.15.0-151.157
ubuntu/linux-aws<4.15.0-1109.116
4.15.0-1109.116
ubuntu/linux-aws-5.4<5.4.0-1051.53~18.04.1
5.4.0-1051.53~18.04.1
ubuntu/linux-azure-4.15<4.15.0-1121.134
4.15.0-1121.134
ubuntu/linux-azure-5.4<5.4.0-1051.53~18.04.1
5.4.0-1051.53~18.04.1
ubuntu/linux-dell300x<4.15.0-1027.32
4.15.0-1027.32
ubuntu/linux-gcp-4.15<4.15.0-1106.120
4.15.0-1106.120
ubuntu/linux-gcp-5.4<5.4.0-1046.49~18.04.1
5.4.0-1046.49~18.04.1
ubuntu/linux-gke-5.4<5.4.0-1046.48~18.04.1
5.4.0-1046.48~18.04.1
ubuntu/linux-gkeop-5.4<5.4.0-1018.19~18.04.1
5.4.0-1018.19~18.04.1
ubuntu/linux-hwe-5.4<5.4.0-77.86~18.04.1
5.4.0-77.86~18.04.1
ubuntu/linux-kvm<4.15.0-1097.99
4.15.0-1097.99
ubuntu/linux-oracle<4.15.0-1078.86
4.15.0-1078.86
ubuntu/linux-oracle-5.4<5.4.0-1048.52~18.04.1
5.4.0-1048.52~18.04.1
ubuntu/linux-raspi-5.4<5.4.0-1038.41~18.04.1
5.4.0-1038.41~18.04.1
ubuntu/linux-raspi2<4.15.0-1092.98
4.15.0-1092.98
ubuntu/linux-snapdragon<4.15.0-1109.118
4.15.0-1109.118
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<4.15.0-2051.53
4.15.0-2051.53
ubuntu/linux-azure-fips<4.15.0-2033.37
4.15.0-2033.37
ubuntu/linux-fips<4.15.0-1066.75
4.15.0-1066.75
ubuntu/linux-gcp-fips<4.15.0-2016.18
4.15.0-2016.18
ubuntu/linux-aws-fips*
ubuntu/linux-azure-fips*
ubuntu/linux-fips*
ubuntu/linux-gcp-fips*
ubuntu/linux<5.4.0-77.86
5.4.0-77.86
ubuntu/linux-aws<5.4.0-1051.53
5.4.0-1051.53
ubuntu/linux-aws-5.8<5.8.0-1038.40~20.04.1
5.8.0-1038.40~20.04.1
ubuntu/linux-azure<5.4.0-1051.53
5.4.0-1051.53
ubuntu/linux-azure-5.8<5.8.0-1036.38~20.04.1
5.8.0-1036.38~20.04.1
ubuntu/linux-bluefield<5.4.0-1013.16
5.4.0-1013.16
ubuntu/linux-gcp<5.4.0-1046.49
5.4.0-1046.49
ubuntu/linux-gcp-5.8<5.8.0-1035.37~20.04.1
5.8.0-1035.37~20.04.1
ubuntu/linux-gke<5.4.0-1046.48
5.4.0-1046.48
ubuntu/linux-gkeop<5.4.0-1018.19
5.4.0-1018.19
ubuntu/linux-hwe-5.8<5.8.0-59.66~20.04.1
5.8.0-59.66~20.04.1
ubuntu/linux-kvm<5.4.0-1041.42
5.4.0-1041.42
ubuntu/linux-oem-5.10<5.10.0-1029.30
5.10.0-1029.30
ubuntu/linux-oracle<5.4.0-1048.52
5.4.0-1048.52
ubuntu/linux-oracle-5.8<5.8.0-1033.34~20.04.1
5.8.0-1033.34~20.04.1
ubuntu/linux-raspi<5.4.0-1038.41
5.4.0-1038.41
ubuntu/linux-riscv-5.8<5.8.0-29.31~20.04.1
5.8.0-29.31~20.04.1
ubuntu/linux-azure-fde-5.15<5.15.0-1114.123~20.04.1
5.15.0-1114.123~20.04.1
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-fips<5.4.0-1028.32
5.4.0-1028.32
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-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-rt to a version that resolves this vulnerability.

    Fixed in 0:4.18.0-348.rt7.130.el8
  2. Upgrade

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

    Fixed in 0:4.18.0-348.el8
  3. Upgrade

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

    Fixed in 5.12
  4. Upgrade

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

    Fixed in 5.10.223-1Fixed in 5.10.234-1Fixed in 6.1.129-1Fixed in 6.1.135-1Fixed in 6.12.25-1Fixed in 6.12.27-1
  5. Upgrade

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

    Fixed in :2021-10-05
  6. Upgrade

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

    Fixed in 4.15.0-1121.134~14.04.1
  7. Upgrade

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

    Fixed in 4.15.0-1109.116~16.04.1
  8. Upgrade

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

    Fixed in 4.15.0-1121.134~16.04.1
  9. Upgrade

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

    Fixed in 4.15.0-1106.120~16.04.1
  10. Upgrade

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

    Fixed in 4.15.0-151.157~16.04.1
  11. Upgrade

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

    Fixed in 4.15.0-1078.86~16.04.1
  12. Upgrade

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

    Fixed in 4.15.0-151.157
  13. Upgrade

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

    Fixed in 4.15.0-1109.116
  14. Upgrade

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

    Fixed in 5.4.0-1051.53~18.04.1
  15. Upgrade

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

    Fixed in 4.15.0-1121.134
  16. Upgrade

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

    Fixed in 5.4.0-1051.53~18.04.1
  17. Upgrade

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

    Fixed in 4.15.0-1027.32
  18. Upgrade

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

    Fixed in 4.15.0-1106.120
  19. Upgrade

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

    Fixed in 5.4.0-1046.49~18.04.1
  20. Upgrade

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

    Fixed in 5.4.0-1046.48~18.04.1
  21. Upgrade

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

    Fixed in 5.4.0-1018.19~18.04.1
  22. Upgrade

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

    Fixed in 5.4.0-77.86~18.04.1
  23. Upgrade

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

    Fixed in 4.15.0-1097.99
  24. Upgrade

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

    Fixed in 4.15.0-1078.86
  25. Upgrade

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

    Fixed in 5.4.0-1048.52~18.04.1
  26. Upgrade

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

    Fixed in 5.4.0-1038.41~18.04.1
  27. Upgrade

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

    Fixed in 4.15.0-1092.98
  28. Upgrade

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

    Fixed in 4.15.0-1109.118
  29. Upgrade

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

    Fixed in 4.15.0-2051.53
  30. Upgrade

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

    Fixed in 4.15.0-2033.37
  31. Upgrade

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

    Fixed in 4.15.0-1066.75
  32. Upgrade

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

    Fixed in 4.15.0-2016.18
  33. Upgrade

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

    Fixed in 5.4.0-77.86
  34. Upgrade

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

    Fixed in 5.4.0-1051.53
  35. Upgrade

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

    Fixed in 5.8.0-1038.40~20.04.1
  36. Upgrade

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

    Fixed in 5.4.0-1051.53
  37. Upgrade

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

    Fixed in 5.8.0-1036.38~20.04.1
  38. Upgrade

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

    Fixed in 5.4.0-1013.16
  39. Upgrade

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

    Fixed in 5.4.0-1046.49
  40. Upgrade

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

    Fixed in 5.8.0-1035.37~20.04.1
  41. Upgrade

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

    Fixed in 5.4.0-1046.48
  42. Upgrade

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

    Fixed in 5.4.0-1018.19
  43. Upgrade

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

    Fixed in 5.8.0-59.66~20.04.1
  44. Upgrade

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

    Fixed in 5.4.0-1041.42
  45. Upgrade

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

    Fixed in 5.10.0-1029.30
  46. Upgrade

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

    Fixed in 5.4.0-1048.52
  47. Upgrade

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

    Fixed in 5.8.0-1033.34~20.04.1
  48. Upgrade

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

    Fixed in 5.4.0-1038.41
  49. Upgrade

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

    Fixed in 5.8.0-29.31~20.04.1
  50. Upgrade

    Upgrade ubuntu/linux-azure-fde-5.15 to a version that resolves this vulnerability.

    Fixed in 5.15.0-1114.123~20.04.1
  51. Upgrade

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

    Fixed in 5.4.0-1069.73+fips2
  52. Upgrade

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

    Fixed in 5.4.0-1073.76+fips1
  53. Upgrade

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

    Fixed in 5.4.0-1028.32
  54. Upgrade

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

    Fixed in 5.4.0-1067.71~20.04.1
  55. Configuration

    Set kernel.unprivileged_bpf_disabled to 1 to prevent unprivileged users from using eBPF and mitigate the flaw.

    Linux kernel eBPF kernel.unprivileged_bpf_disabled = 1

Event History

Apr 18, 2021
CVE Published
12:00 AM
Apr 20, 2021
CVE Published
via MITRE·12:00 AM
Data Sourced
via MITRE·12:00 AM
Description
Data Sourced
via OSV·04:15 PM
DescriptionSeverityAffected Software
Jun 3, 2021
Exploit Published
via GitHub·03:53 PM
Oct 1, 2021
Advisory Published
via OSV·12:00 AM

Parent advisories

This vulnerability appears in the following advisories.

Frequently Asked Questions

1

What is the severity of CVE-2021-29155?

The severity of CVE-2021-29155 is categorized as critical due to its potential to allow local attackers to bypass security mechanisms.

2

How do I fix CVE-2021-29155?

To fix CVE-2021-29155, update your Linux kernel to the latest version as specified in the security advisories.

3

What systems are affected by CVE-2021-29155?

CVE-2021-29155 affects various versions of the Linux kernel, particularly those prior to version 5.12 and specific Red Hat kernel packages.

4

What is the exploitability of CVE-2021-29155?

CVE-2021-29155 is exploitable by local users with special privileges, which may lead to unauthorized access or manipulation of system memory.

5

Is CVE-2021-29155 related to Spectre vulnerabilities?

Yes, CVE-2021-29155 is a vulnerability that pertains to the Linux kernel's mechanism designed to mitigate Spectre-related issues.

Company

Resources

Contact

SecAlerts Pty Ltd.
132 Wickham Terrace
Fortitude Valley,
QLD 4006, Australia
info@secalerts.co
By using SecAlerts services, you agree to our services end-user license agreement. This website is safeguarded by reCAPTCHA and governed by the Google Privacy Policy and Terms of Service. All names, logos, and brands of products are owned by their respective owners, and any usage of these names, logos, and brands for identification purposes only does not imply endorsement. If you possess any content that requires removal, please get in touch with us.
© 2026 SecAlerts Pty Ltd.
ABN: 70 645 966 203, ACN: 645 966 203