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CVE-2020-8835

Publication date 30 March 2020

Last updated 24 July 2024

Ubuntu priority

High

Why this priority?

Cvss 3 Severity Score

7.8 · High

Score breakdown

In the Linux kernel 5.5.0 and newer, the bpf verifier (kernel/bpf/verifier.c) did not properly restrict the register bounds for 32-bit operations, leading to out-of-bounds reads and writes in kernel memory. The vulnerability also affects the Linux 5.4 stable series, starting with v5.4.7, as the introducing commit was backported to that branch. This vulnerability was fixed in 5.6.1, 5.5.14, and 5.4.29. (issue is aka ZDI-CAN-10780)

From the Ubuntu Security Team

Manfred Paul discovered that the bpf verifier in the Linux kernel did not properly calculate register bounds for certain operations. A local attacker could use this to expose sensitive information (kernel memory) or gain administrative privileges.

Read the notes from the security team

Mitigation

Mitigation for this vulnerability is available by setting the kernel.unprivileged_bpf_disabled sysctl to 1: $ sudo sysctl kernel.unprivileged_bpf_disabled=1 $ echo kernel.unprivileged_bpf_disabled=1 | \ sudo tee /etc/sysctl.d/90-CVE-2020-8835.conf This issue is also mitigated on systems that use secure boot, thanks to the kernel lockdown feature which blocks BPF program loading.

Status

Package Ubuntu Release Status
linux 20.04 LTS focal
Not affected
19.10 eoan
Fixed 5.3.0-45.37
18.04 LTS bionic
Not affected
16.04 LTS xenial
Not affected
14.04 LTS trusty
Not affected
linux-aws 20.04 LTS focal
Not affected
19.10 eoan
Fixed 5.3.0-1015.16
18.04 LTS bionic
Not affected
16.04 LTS xenial
Not affected
14.04 LTS trusty
Not affected
linux-aws-5.0 20.04 LTS focal Not in release
19.10 eoan Not in release
18.04 LTS bionic
Not affected
16.04 LTS xenial Not in release
14.04 LTS trusty Not in release
linux-aws-hwe 20.04 LTS focal Not in release
19.10 eoan Not in release
18.04 LTS bionic Not in release
16.04 LTS xenial
Not affected
14.04 LTS trusty Not in release
linux-azure 20.04 LTS focal
Not affected
19.10 eoan
Fixed 5.3.0-1018.19
18.04 LTS bionic
Not affected
16.04 LTS xenial
Not affected
14.04 LTS trusty
Not affected
linux-azure-5.3 20.04 LTS focal Not in release
19.10 eoan Not in release
18.04 LTS bionic
Fixed 5.3.0-1018.19~18.04.1
16.04 LTS xenial Not in release
14.04 LTS trusty Not in release
linux-azure-edge 20.04 LTS focal Not in release
19.10 eoan Not in release
18.04 LTS bionic Ignored end of life, was needs-triage
16.04 LTS xenial Ignored end of standard support, was needs-triage
14.04 LTS trusty Not in release
linux-gcp 20.04 LTS focal
Not affected
19.10 eoan
Fixed 5.3.0-1016.17
18.04 LTS bionic
Not affected
16.04 LTS xenial
Not affected
14.04 LTS trusty Not in release
linux-gcp-5.3 20.04 LTS focal Not in release
19.10 eoan Not in release
18.04 LTS bionic
Fixed 5.3.0-1016.17~18.04.1
16.04 LTS xenial Not in release
14.04 LTS trusty Not in release
linux-gcp-edge 20.04 LTS focal Not in release
19.10 eoan Not in release
18.04 LTS bionic Ignored end of life, was needs-triage
16.04 LTS xenial Not in release
14.04 LTS trusty Not in release
linux-gke-4.15 20.04 LTS focal Not in release
19.10 eoan Not in release
18.04 LTS bionic
Not affected
16.04 LTS xenial Not in release
14.04 LTS trusty Not in release
linux-gke-5.0 20.04 LTS focal Not in release
19.10 eoan Not in release
18.04 LTS bionic
Not affected
16.04 LTS xenial Not in release
14.04 LTS trusty Not in release
linux-gke-5.3 20.04 LTS focal Not in release
19.10 eoan Not in release
18.04 LTS bionic
Fixed 5.3.0-1016.17~18.04.1
16.04 LTS xenial Not in release
14.04 LTS trusty Not in release
linux-hwe 20.04 LTS focal Not in release
19.10 eoan Not in release
18.04 LTS bionic
Fixed 5.3.0-45.37~18.04.1
16.04 LTS xenial
Not affected
14.04 LTS trusty Not in release
linux-hwe-edge 20.04 LTS focal Not in release
19.10 eoan Not in release
18.04 LTS bionic Ignored end of life, was needs-triage
16.04 LTS xenial
Not affected
14.04 LTS trusty Not in release
linux-kvm 20.04 LTS focal
Not affected
19.10 eoan
Fixed 5.3.0-1014.15
18.04 LTS bionic
Not affected
16.04 LTS xenial
Not affected
14.04 LTS trusty Not in release
linux-lts-trusty 20.04 LTS focal Not in release
19.10 eoan Not in release
18.04 LTS bionic Not in release
16.04 LTS xenial Not in release
14.04 LTS trusty Not in release
linux-lts-xenial 20.04 LTS focal Not in release
19.10 eoan Not in release
18.04 LTS bionic Not in release
16.04 LTS xenial Not in release
14.04 LTS trusty
Not affected
linux-oem 20.04 LTS focal Not in release
19.10 eoan
Not affected
18.04 LTS bionic
Not affected
16.04 LTS xenial
Not affected
14.04 LTS trusty Not in release
linux-oem-5.6 20.04 LTS focal
Not affected
19.10 eoan Not in release
18.04 LTS bionic Not in release
16.04 LTS xenial Not in release
14.04 LTS trusty Not in release
linux-oem-osp1 20.04 LTS focal Not in release
19.10 eoan
Not affected
18.04 LTS bionic
Not affected
16.04 LTS xenial Not in release
14.04 LTS trusty Not in release
linux-oracle 20.04 LTS focal
Not affected
19.10 eoan
Fixed 5.3.0-1013.14
18.04 LTS bionic
Not affected
16.04 LTS xenial
Not affected
14.04 LTS trusty Not in release
linux-oracle-5.0 20.04 LTS focal Not in release
19.10 eoan Not in release
18.04 LTS bionic
Not affected
16.04 LTS xenial Not in release
14.04 LTS trusty Not in release
linux-oracle-5.3 20.04 LTS focal Not in release
19.10 eoan Not in release
18.04 LTS bionic
Fixed 5.3.0-1013.14~18.04.1
16.04 LTS xenial Not in release
14.04 LTS trusty Not in release
linux-raspi2 20.04 LTS focal Ignored end of life, was needs-triage
19.10 eoan
Fixed 5.3.0-1021.23
18.04 LTS bionic
Not affected
16.04 LTS xenial
Not affected
14.04 LTS trusty Not in release
linux-raspi2-5.3 20.04 LTS focal Not in release
19.10 eoan Not in release
18.04 LTS bionic
Fixed 5.3.0-1021.23~18.04.1
16.04 LTS xenial Not in release
14.04 LTS trusty Not in release
linux-snapdragon 20.04 LTS focal Not in release
19.10 eoan Not in release
18.04 LTS bionic
Not affected
16.04 LTS xenial
Not affected
14.04 LTS trusty Not in release

Notes

sbeattie

introduced by upstream commit 581738a681b6, which was mistakenly backported to upstream stable 5.4 kernel (b4de258dede528f88f401259aab3147fb6da1ddf). Ubuntu's 5.3 kernels are affected because 5.4 stable backport commits were pulled into Ubuntu's 5.3 kernels.

Patch details

For informational purposes only. We recommend not to cherry-pick updates. How can I get the fixes?

Package Patch details
linux

Severity score breakdown

Parameter Value
Base score 7.8 · High
Attack vector Local
Attack complexity High
Privileges required Low
User interaction None
Scope Changed
Confidentiality High
Integrity impact High
Availability impact High
Vector CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:H