Description
An issue was discovered in drivers/firmware/efi/efi.c in the Linux kernel before 5.4. Incorrect access permissions for the efivar_ssdt ACPI variable could be used by attackers to bypass lockdown or secure boot restrictions, aka CID-1957a85b0032.
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 | 5.2.6-1 | — |
| Debian 13 | linux | 5.2.6-1 | — |
| Debian 12 | linux | 5.2.6-1 | — |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| 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 | 4.15.0-112.113 | USN-4426-1 |
| Ubuntu 18.04 LTS | linux-aws | 4.15.0-1079.83 | USN-4426-1 |
| Ubuntu 18.04 LTS | linux-aws-5.3 | 5.3.0-1032.34~18.04.2 | USN-4440-1 |
| Ubuntu 18.04 LTS | linux-azure-4.15 | 4.15.0-1092.102 | USN-4426-1 |
| Ubuntu 18.04 LTS | linux-azure-5.3 | 5.3.0-1034.35~18.04.1 | USN-4440-1 |
| Ubuntu 18.04 LTS | linux-gcp +6 | No fix yet | — |
| Ubuntu 18.04 LTS | linux-gcp-4.15 | 4.15.0-1080.90 | USN-4426-1 |
| Ubuntu 18.04 LTS | linux-gcp-5.3 +1 | 5.3.0-1032.34~18.04.1 | USN-4440-1 |
| Ubuntu 18.04 LTS | linux-gke-4.15 | 4.15.0-1066.69 | USN-4426-1 |
| Ubuntu 18.04 LTS | linux-gke-5.0 | 5.0.0-1045.46 | USN-4439-1 |
| Ubuntu 18.04 LTS | linux-hwe | 5.3.0-64.58~18.04.1 | USN-4440-1 |
| Ubuntu 18.04 LTS | linux-kvm | 4.15.0-1071.72 | USN-4426-1 |
| Ubuntu 18.04 LTS | linux-oem | 4.15.0-1093.103 | USN-4426-1 |
| Ubuntu 18.04 LTS | linux-oem-osp1 | 5.0.0-1065.70 | USN-4439-1 |
| Ubuntu 18.04 LTS | linux-oracle | 4.15.0-1050.54 | USN-4426-1 |
| Ubuntu 18.04 LTS | linux-oracle-5.3 | 5.3.0-1030.32~18.04.1 | USN-4440-1 |
| Ubuntu 18.04 LTS | linux-raspi2 | 4.15.0-1067.71 | USN-4426-1 |
| Ubuntu 18.04 LTS | linux-raspi2-5.3 | 5.3.0-1030.32~18.04.2 | USN-4440-1 |
| Ubuntu 18.04 LTS | linux-snapdragon | 4.15.0-1083.91 | USN-4426-1 |
| Ubuntu 16.04 LTS | linux | 4.4.0-186.216 | USN-4427-1 |
| Ubuntu 16.04 LTS | linux-aws | 4.4.0-1111.123 | USN-4427-1 |
| Ubuntu 16.04 LTS | linux-aws-hwe | 4.15.0-1079.83~16.04.1 | USN-4426-1 |
| Ubuntu 16.04 LTS | linux-azure | 4.15.0-1092.102~16.04.1 | USN-4426-1 |
| Ubuntu 16.04 LTS | linux-gcp | 4.15.0-1080.90~16.04.1 | USN-4426-1 |
| Ubuntu 16.04 LTS | linux-hwe | 4.15.0-112.113~16.04.1 | USN-4426-1 |
| Ubuntu 16.04 LTS | linux-hwe-edge | No fix yet | — |
| Ubuntu 16.04 LTS | linux-kvm | 4.4.0-1077.84 | USN-4427-1 |
| Ubuntu 16.04 LTS | linux-oracle | 4.15.0-1050.54~16.04.1 | USN-4426-1 |
| Ubuntu 16.04 LTS | linux-raspi2 | 4.4.0-1136.145 | USN-4427-1 |
| Ubuntu 16.04 LTS | linux-snapdragon | 4.4.0-1140.148 | USN-4427-1 |
Show 3 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu Pro FIPS 18.04 LTS | linux-aws-fips +2 | No fix yet | — |
| Ubuntu Pro FIPS-updates 18.04 LTS | linux-aws-fips | 4.15.0-2024.24 | — |
| Ubuntu Pro FIPS-updates 18.04 LTS | linux-azure-fips | 4.15.0-2006.7 | — |
| Ubuntu Pro FIPS-updates 18.04 LTS | linux-fips | 4.15.0-1037.42 | — |
| Ubuntu Pro 14.04 LTS | linux-aws | 4.4.0-1075.79 | USN-4427-1 |
| Ubuntu Pro 14.04 LTS | linux-azure | 4.15.0-1092.102~14.04.1 | — |
| Ubuntu Pro 14.04 LTS | linux-lts-xenial | 4.4.0-186.216~14.04.1 | USN-4427-1 |
Red Hat
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| RHEL 8 | kernel-rt +12 | 4.18.0-193.14.3.rt13.67.el8_2 | RHSA-2020:3219 |
| RHEL 8 | perf +28 | 4.18.0-193.14.3.el8_2 | RHSA-2020:3218 |
Show 2 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| RHEL 8.1 EUS | perf +26 | 4.18.0-147.24.2.el8_1 | RHSA-2020:3222 |
| RHEL 8.0 E4S | perf +20 | 4.18.0-80.27.2.el8_0 | RHSA-2020:3228 |
SUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES 15 SP1 | kernel-azure +2 | 4.12.14-8.38.1 | SUSE-SU-2020:2103-1 |
| SLES 15 SP1 | kernel-docs +5 | 4.12.14-197.48.1 | SUSE-SU-2020:2107-1 |
| SLES 15 | kernel-docs +6 | 4.12.14-150.55.1 | SUSE-SU-2020:2106-1 |
| SLES 12 SP5 | kernel-azure +2 | 4.12.14-16.22.1 | SUSE-SU-2020:2119-1 |
| SLES 12 SP5 | kernel-docs +4 | 4.12.14-122.29.1 | SUSE-SU-2020:2122-1 |
| SLES 12 SP4 | kernel-syms +2 | 4.12.14-95.57.1 | SUSE-SU-2020:2121-1 |
Show 12 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES for SAP 15 | kernel-docs +5 | 4.12.14-150.55.1 | SUSE-SU-2020:2106-1 |
| SLES for SAP 12 SP5 | kernel-azure +2 | 4.12.14-16.22.1 | SUSE-SU-2020:2119-1 |
| SLES for SAP 12 SP5 | kernel-syms +2 | 4.12.14-122.29.1 | SUSE-SU-2020:2122-1 |
| SLES for SAP 12 SP4 | kernel-syms +2 | 4.12.14-95.57.1 | SUSE-SU-2020:2121-1 |
| SLE Real Time 12 SP5 | kernel-rt +3 | 4.12.14-10.13.1 | SUSE-SU-2020:2478-1 |
| SLE Live Patching 15 SP1 | kernel-default | 4.12.14-197.48.1 | SUSE-SU-2020:2107-1 |
| SLE Live Patching 15 SP1 | kernel-livepatch-SLE15-SP1_Update_13 | 1-3.3.1 | SUSE-SU-2020:2107-1 |
| SLE Live Patching 15 | kernel-default | 4.12.14-150.55.1 | SUSE-SU-2020:2106-1 |
| SLE Live Patching 15 | kernel-livepatch-SLE15_Update_19 | 1-1.3.1 | SUSE-SU-2020:2106-1 |
| SLE Live Patching 12 SP5 | kernel-default | 4.12.14-122.29.1 | SUSE-SU-2020:2122-1 |
| SLE Live Patching 12 SP5 | kgraft-patch-SLE12-SP5_Update_7 | 1-8.3.1 | SUSE-SU-2020:2122-1 |
| SLE Live Patching 12 SP4 | kernel-default | 4.12.14-95.57.1 | SUSE-SU-2020:2121-1 |
| SLE Live Patching 12 SP4 | kgraft-patch-SLE12-SP4_Update_15 | 1-6.3.1 | SUSE-SU-2020:2121-1 |
| SLE HPC 15 | kernel-docs +5 | 4.12.14-150.55.1 | SUSE-SU-2020:2106-1 |
| SUSE Real Time Module 15 SP1 | kernel-rt +3 | 4.12.14-14.28.1 | SUSE-SU-2020:2487-1 |
| SUSE OpenStack Cloud Crowbar 9 | kernel-syms +2 | 4.12.14-95.57.1 | SUSE-SU-2020:2121-1 |
| SUSE OpenStack Cloud 9 | kernel-syms +2 | 4.12.14-95.57.1 | SUSE-SU-2020:2121-1 |
openSUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| openSUSE Leap 15.1 | kernel-docs +8 | 4.12.14-lp151.28.59.1 | openSUSE-SU-2020:1153-1 |
Oracle Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Oracle Linux 8 | perf +19 | 4.18.0-193.14.3.el8_2 | ELSA-2020-3218 |
| Oracle Linux 7 | perf +10 | 4.14.35-1902.304.6.3.el7uek | ELSA-2020-5804, ELSA-2020-5791 |
Advisories 20
- RHSA-2020:3228 Red Hat Security Advisory: kernel security and bug fix update Red Hat Security Advisories (RHSA) · Jun 29, 2026
- RHSA-2020:3222 Red Hat Security Advisory: kernel security and bug fix update Red Hat Security Advisories (RHSA) · Jun 29, 2026
- RHSA-2020:3218 Red Hat Security Advisory: kernel security and bug fix update Red Hat Security Advisories (RHSA) · Jun 29, 2026
- RHSA-2020:3219 Red Hat Security Advisory: kernel-rt security and bug fix update Red Hat Security Advisories (RHSA) · Jun 29, 2026
- USN-4440-1 linux-hwe, linux-aws-5.3, linux-azure-5.3, linux-gcp-5.3, linux-gke-5.3, linux-hwe, linux-oracle-5.3, linux-raspi2-5.3 vulnerabilities Ubuntu Security Notices (USN) · Jun 3, 2026
- USN-4439-1 linux-gke-5.0, linux-oem-osp1 vulnerabilities Ubuntu Security Notices (USN) · Jun 3, 2026
- USN-4427-1 linux, linux-aws, linux-kvm, linux-lts-xenial, linux-raspi2, linux-snapdragon vulnerabilities Ubuntu Security Notices (USN) · Jun 3, 2026
- USN-4426-1 linux, linux-aws, linux-aws-hwe, linux-azure, linux-azure-4.15, linux-gcp, linux-gcp-4.15, linux-gke-4.15, linux-hwe, linux-kvm, linux-oem, linux-oracle, linux-raspi2, linux-snapdragon vulnerabilities Ubuntu Security Notices (USN) · Jun 3, 2026
- openSUSE-SU-2020:1153-1 Security update for the Linux Kernel SUSE / openSUSE Security Updates · Feb 4, 2026
- SUSE-SU-2020:2119-1 Security update for the Linux Kernel SUSE / openSUSE Security Updates · Feb 4, 2026
- SUSE-SU-2020:2487-1 Security update for the Linux Kernel SUSE / openSUSE Security Updates · Feb 4, 2026
- SUSE-SU-2020:2107-1 Security update for the Linux Kernel SUSE / openSUSE Security Updates · Feb 4, 2026
- SUSE-SU-2020:2121-1 Security update for the Linux Kernel SUSE / openSUSE Security Updates · Feb 4, 2026
- SUSE-SU-2020:2122-1 Security update for the Linux Kernel SUSE / openSUSE Security Updates · Feb 4, 2026
- SUSE-SU-2020:2478-1 Security update for the Linux Kernel SUSE / openSUSE Security Updates · Feb 4, 2026
- SUSE-SU-2020:2103-1 Security update for the Linux Kernel SUSE / openSUSE Security Updates · Feb 4, 2026
- SUSE-SU-2020:2106-1 Security update for the Linux Kernel SUSE / openSUSE Security Updates · May 2, 2025
- ELSA-2020-5804 Important: Unbreakable Enterprise kernel security update (Oracle Linux 7) Oracle Linux Security Advisories (ELSA) · Aug 10, 2020
- ELSA-2020-3218 Moderate: kernel security and bug fix update (Oracle Linux 8) Oracle Linux Security Advisories (ELSA) · Jul 30, 2020
- ELSA-2020-5791 Important: Unbreakable Enterprise kernel security update (Oracle Linux 7) Oracle Linux Security Advisories (ELSA) · Jul 29, 2020
References
- https://git.zx2c4.com/american-unsigned-language/tree/american-unsigned-language.sh
- https://mailarchives.bentasker.co.uk/Mirrors/OSSSec/2020/06-Jun/msg00035.html
- https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=1957a85b0032a81e6482ca4aab883643b8dae06e
- https://cdn.kernel.org/pub/linux/kernel/v5.x/ChangeLog-5.4
- [oss-security] 20200720 Re: Re: lockdown bypass on ubuntu 18.04's 4.15 kernel for loading unsigned modules mailing-list
- USN-4427-1 vendor-advisory
- [oss-security] 20200729 multiple secure boot grub2 and linux kernel vulnerabilities mailing-list
- [oss-security] 20200730 Re: UEFI SecureBoot bypass fixes rolled out to kernels below radar mailing-list
- [oss-security] 20200730 UEFI SecureBoot bypass fixes rolled out to kernels below radar mailing-list
- USN-4439-1 vendor-advisory
- USN-4426-1 vendor-advisory
- USN-4440-1 vendor-advisory
- openSUSE-SU-2020:1153 vendor-advisory