Description
In the Linux kernel before 4.20.2, kernel/sched/fair.c mishandles leaf cfs_rq's, which allows attackers to cause a denial of service (infinite loop in update_blocked_averages) or possibly have unspecified other impact by inducing a high load.
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
Debian
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian 14 | linux | 4.19.16-1 | — |
| Debian 13 | linux | 4.19.16-1 | — |
| Debian 12 | linux | 4.19.16-1 | — |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 26.04 LTS | linux-vmware | No fix yet | — |
| Ubuntu 24.04 LTS | linux-raspi-realtime | No fix yet | — |
| Ubuntu 22.04 LTS | linux-riscv +2 | No fix yet | — |
| Ubuntu 20.04 LTS | linux-gke +2 | No fix yet | — |
| Ubuntu 18.04 LTS | linux | 4.15.0-60.67 | USN-4115-1 |
| Ubuntu 18.04 LTS | linux-aws | 4.15.0-1047.49 | USN-4118-1 |
| Ubuntu 18.04 LTS | linux-azure | 5.0.0-1014.14~18.04.1 | — |
| Ubuntu 18.04 LTS | linux-gcp | 4.15.0-1042.45 | — |
| Ubuntu 18.04 LTS | linux-gke-4.15 | 4.15.0-1041.43 | USN-4115-1 |
| Ubuntu 18.04 LTS | linux-hwe | 5.0.0-23.24~18.04.1 | — |
| Ubuntu 18.04 LTS | linux-kvm | 4.15.0-1043.43 | USN-4115-1 |
| Ubuntu 18.04 LTS | linux-oem | 4.15.0-1056.65 | — |
| Ubuntu 18.04 LTS | linux-oracle | 4.15.0-1022.25 | USN-4115-1 |
| Ubuntu 18.04 LTS | linux-raspi2 | 4.15.0-1044.47 | USN-4115-1 |
| Ubuntu 18.04 LTS | linux-snapdragon | 4.15.0-1062.69 | — |
Show 6 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 16.04 LTS | linux | 4.4.0-170.199 | USN-4211-1 |
| Ubuntu 16.04 LTS | linux-aws | 4.4.0-1099.110 | USN-4211-1 |
| Ubuntu 16.04 LTS | linux-aws-hwe | 4.15.0-1047.49~16.04.1 | USN-4118-1 |
| Ubuntu 16.04 LTS | linux-azure | 4.15.0-1056.61 | USN-4115-1 |
| Ubuntu 16.04 LTS | linux-gcp | 4.15.0-1041.43 | USN-4115-1 |
| Ubuntu 16.04 LTS | linux-hwe | 4.15.0-60.67~16.04.1 | USN-4115-1 |
| Ubuntu 16.04 LTS | linux-kvm | 4.4.0-1063.70 | USN-4211-1 |
| Ubuntu 16.04 LTS | linux-oracle | 4.15.0-1022.25~16.04.1 | USN-4115-1 |
| Ubuntu 16.04 LTS | linux-raspi2 | 4.4.0-1126.135 | USN-4211-1 |
| Ubuntu 16.04 LTS | linux-snapdragon | 4.4.0-1130.138 | USN-4211-1 |
| Ubuntu Pro FIPS 18.04 LTS | linux-aws-fips +2 | No fix yet | — |
| Ubuntu Pro FIPS 16.04 LTS | linux-fips | No fix yet | — |
| Ubuntu Pro FIPS-updates 18.04 LTS | linux-aws-fips | 4.15.0-2018.18 | — |
| Ubuntu Pro FIPS-updates 18.04 LTS | linux-azure-fips | 4.15.0-2006.7 | — |
| Ubuntu Pro FIPS-updates 16.04 LTS | linux-fips | 4.4.0-1026.31 | — |
| Ubuntu Pro 14.04 LTS | linux-aws | 4.4.0-1059.63 | USN-4211-2 |
| Ubuntu Pro 14.04 LTS | linux-azure | 4.15.0-1059.64~14.04.1 | — |
| Ubuntu Pro 14.04 LTS | linux-lts-xenial | 4.4.0-170.199~14.04.1 | USN-4211-2 |
Red Hat
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| RHEL 8 | kernel-rt +12 | 4.18.0-80.7.1.rt9.153.el8_0 | RHSA-2019:1971 |
| RHEL 8 | perf +26 | 4.18.0-80.7.1.el8_0 | RHSA-2019:1959 |
SUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES 12 SP3 | kernel-default | 4.4.180-94.164.3 | SUSE-SU-2022:2082-1 |
| SLES 12 SP3 | kernel-syms +1 | 4.4.180-94.164.2 | SUSE-SU-2022:2082-1 |
| SLES 12 SP3 | kgraft-patch-SLE12-SP3_Update_45 | 1-4.3.2 | SUSE-SU-2022:2082-1 |
| SLES 12 SP2 | kernel-syms +2 | 4.4.121-92.175.2 | SUSE-SU-2023:3324-1, SUSE-SU-2023:2805-1, SUSE-SU-2022:2077-1 |
Show 4 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES for SAP 12 SP3 | kernel-default | 4.4.180-94.164.3 | SUSE-SU-2022:2082-1 |
| SLES for SAP 12 SP3 | kernel-syms +1 | 4.4.180-94.164.2 | SUSE-SU-2022:2082-1 |
| SLES for SAP 12 SP3 | kgraft-patch-SLE12-SP3_Update_45 | 1-4.3.2 | SUSE-SU-2022:2082-1 |
| SUSE OpenStack Cloud Crowbar 8 | kernel-default | 4.4.180-94.164.3 | SUSE-SU-2022:2082-1 |
| SUSE OpenStack Cloud Crowbar 8 | kernel-syms +1 | 4.4.180-94.164.2 | SUSE-SU-2022:2082-1 |
| SUSE OpenStack Cloud Crowbar 8 | kgraft-patch-SLE12-SP3_Update_45 | 1-4.3.2 | SUSE-SU-2022:2082-1 |
| SUSE OpenStack Cloud 8 | kernel-default | 4.4.180-94.164.3 | SUSE-SU-2022:2082-1 |
| SUSE OpenStack Cloud 8 | kernel-syms +1 | 4.4.180-94.164.2 | SUSE-SU-2022:2082-1 |
| SUSE OpenStack Cloud 8 | kgraft-patch-SLE12-SP3_Update_45 | 1-4.3.2 | SUSE-SU-2022:2082-1 |
| SUSE HPE Helion OpenStack 8 | kernel-default | 4.4.180-94.164.3 | SUSE-SU-2022:2082-1 |
| SUSE HPE Helion OpenStack 8 | kernel-syms +1 | 4.4.180-94.164.2 | SUSE-SU-2022:2082-1 |
| SUSE HPE Helion OpenStack 8 | kgraft-patch-SLE12-SP3_Update_45 | 1-4.3.2 | SUSE-SU-2022:2082-1 |
Oracle Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Oracle Linux 8 | perf +19 | 4.18.0-80.7.1.el8_0 | ELSA-2019-1959 |
Advisories 11
- USN-4211-1 linux, linux-aws, linux-kvm, linux-raspi2, linux-snapdragon vulnerabilities Ubuntu Security Notices (USN) · Sep 9, 2026
- USN-4211-2 linux-lts-xenial, linux-aws vulnerabilities Ubuntu Security Notices (USN) · Sep 9, 2026
- USN-4115-1 linux, linux-azure, linux-gcp, linux-gke-4.15, linux-hwe, linux-kvm, linux-oracle, linux-raspi2 vulnerabilities Ubuntu Security Notices (USN) · Sep 7, 2026
- USN-4118-1 linux-aws vulnerabilities Ubuntu Security Notices (USN) · Sep 7, 2026
- RHSA-2019:1971 Red Hat Security Advisory: kernel-rt security and bug fix update Red Hat Security Advisories (RHSA) · Jun 28, 2026
- RHSA-2019:1959 Red Hat Security Advisory: kernel security, bug fix, and enhancement update Red Hat Security Advisories (RHSA) · Jun 28, 2026
- SUSE-SU-2022:2077-1 Security update for the Linux Kernel SUSE / openSUSE Security Updates · Feb 4, 2026
- SUSE-SU-2023:2805-1 Security update for the Linux Kernel SUSE / openSUSE Security Updates · Feb 4, 2026
- SUSE-SU-2022:2082-1 Security update for the Linux Kernel SUSE / openSUSE Security Updates · Feb 4, 2026
- SUSE-SU-2023:3324-1 Security update for the Linux Kernel SUSE / openSUSE Security Updates · Feb 4, 2026
- ELSA-2019-1959 Important: kernel security, bug fix, and enhancement update (Oracle Linux 8) Oracle Linux Security Advisories (ELSA) · Aug 19, 2019
References
- https://github.com/torvalds/linux/commit/c40f7d74c741a907cfaeb73a7697081881c497d0
- http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=c40f7d74c741a907cfaeb73a7697081881c497d0
- https://cdn.kernel.org/pub/linux/kernel/v4.x/ChangeLog-4.20.2
- RHSA-2019:1959 vendor-advisory
- RHSA-2019:1971 vendor-advisory
- USN-4115-1 vendor-advisory
- USN-4118-1 vendor-advisory
- USN-4211-2 vendor-advisory
- USN-4211-1 vendor-advisory