Description
Overlayfs did not properly perform permission checking when copying up files in an overlayfs and could be exploited from within a user namespace, if, for example, unprivileged user namespaces were allowed. It was possible to have a file not readable by an unprivileged user to be copied to a mountpoint controlled by the user, like a removable device. This was introduced in kernel version 4.19 by commit d1d04ef ("ovl: stack file ops"). This was fixed in kernel version 5.8 by commits 56230d9 ("ovl: verify permissions in ovl_path_open()"), 48bd024 ("ovl: switch to mounter creds in readdir") and 05acefb ("ovl: check permission to open real file"). Additionally, commits 130fdbc ("ovl: pass correct flags for opening real directory") and 292f902 ("ovl: call secutiry hook in ovl_real_ioctl()") in kernel 5.8 might also be desired or necessary. These additional commits introduced a regression in overlay mounts within user namespaces which prevented access to files with ownership outside of the user namespace. This regression was mitigated by subsequent commit b6650da ("ovl: do not fail because of O_NOATIMEi") in kernel 5.11.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| Linux kernel | Linux kernel | 5.11-stable – < 5.11.0 | 5.11.0 |
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 | 5.8.7-1 | — |
| Debian 13 | linux | 5.8.7-1 | — |
| Debian 12 | linux | 5.8.7-1 | — |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 24.04 LTS | linux-raspi-realtime | No fix yet | — |
| Ubuntu 22.04 LTS | linux-riscv +3 | No fix yet | — |
| Ubuntu 20.04 LTS | linux | 5.4.0-51.56 | USN-4576-1 |
| Ubuntu 20.04 LTS | linux-aws +2 | 5.4.0-1028.29 | USN-4576-1 |
| Ubuntu 20.04 LTS | linux-azure | 5.4.0-1031.32 | USN-4576-1 |
| Ubuntu 20.04 LTS | linux-gke +2 | No fix yet | — |
| Ubuntu 20.04 LTS | linux-kvm | 5.4.0-1026.27 | USN-4576-1 |
| Ubuntu 20.04 LTS | linux-oem-5.6 | 5.6.0-1031.32 | — |
| Ubuntu 20.04 LTS | linux-raspi | 5.4.0-1021.24 | USN-4576-1 |
| Ubuntu 20.04 LTS | linux-riscv | 5.4.0-36.41 | — |
| Ubuntu 18.04 LTS | linux | 4.15.0-121.123 | USN-4578-1 |
| Ubuntu 18.04 LTS | linux-aws | 4.15.0-1086.91 | USN-4578-1 |
| Ubuntu 18.04 LTS | linux-aws-5.4 +2 | 5.4.0-1028.29~18.04.1 | USN-4576-1 |
| Ubuntu 18.04 LTS | linux-azure-4.15 | 4.15.0-1099.110 | USN-4578-1 |
| Ubuntu 18.04 LTS | linux-azure-5.4 | 5.4.0-1031.32~18.04.1 | USN-4576-1 |
| Ubuntu 18.04 LTS | linux-gcp +10 | No fix yet | — |
| Ubuntu 18.04 LTS | linux-gcp-4.15 | 4.15.0-1086.98 | USN-4578-1 |
| Ubuntu 18.04 LTS | linux-gke-4.15 | 4.15.0-1072.76 | USN-4578-1 |
| Ubuntu 18.04 LTS | linux-gke-5.0 | 5.0.0-1049.50 | USN-4577-1 |
| Ubuntu 18.04 LTS | linux-gke-5.3 | 5.3.0-1038.40 | USN-4577-1 |
| Ubuntu 18.04 LTS | linux-gke-5.4 | 5.4.0-1027.28~18.04.1 | — |
| Ubuntu 18.04 LTS | linux-gkeop-5.4 | 5.4.0-1003.3 | — |
| Ubuntu 18.04 LTS | linux-hwe | 5.3.0-68.63 | USN-4577-1 |
| Ubuntu 18.04 LTS | linux-hwe-5.4 | 5.4.0-51.56~18.04.1 | USN-4576-1 |
| Ubuntu 18.04 LTS | linux-kvm | 4.15.0-1077.79 | USN-4578-1 |
| Ubuntu 18.04 LTS | linux-oem | 4.15.0-1099.109 | USN-4578-1 |
| Ubuntu 18.04 LTS | linux-oem-osp1 | 5.0.0-1069.75 | USN-4577-1 |
| Ubuntu 18.04 LTS | linux-oracle | 4.15.0-1057.62 | USN-4578-1 |
| Ubuntu 18.04 LTS | linux-raspi-5.4 | 5.4.0-1021.24~18.04.1 | USN-4576-1 |
| Ubuntu 18.04 LTS | linux-raspi2 | 4.15.0-1073.78 | USN-4578-1 |
| Ubuntu 18.04 LTS | linux-raspi2-5.3 | 5.3.0-1035.37 | USN-4577-1 |
| Ubuntu 18.04 LTS | linux-snapdragon | 4.15.0-1089.98 | USN-4578-1 |
| Ubuntu 16.04 LTS | linux-aws-hwe | 4.15.0-1085.90~16.04.1 | USN-4578-1 |
| Ubuntu 16.04 LTS | linux-azure | 4.15.0-1098.109~16.04.1 | USN-4578-1 |
| Ubuntu 16.04 LTS | linux-gcp | 4.15.0-1086.98~16.04.1 | USN-4578-1 |
| Ubuntu 16.04 LTS | linux-hwe | 4.15.0-120.122~16.04.1 | USN-4578-1 |
| Ubuntu 16.04 LTS | linux-hwe-edge | No fix yet | — |
| Ubuntu 16.04 LTS | linux-oracle | 4.15.0-1056.61~16.04.1 | USN-4578-1 |
Show 10 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu Pro FIPS 20.04 LTS | linux-aws-fips +2 | No fix yet | — |
| Ubuntu Pro FIPS 18.04 LTS | linux-fips +3 | No fix yet | — |
| Ubuntu Pro FIPS 16.04 LTS | linux-fips | No fix yet | — |
| Ubuntu Pro FIPS-updates 20.04 LTS | linux-aws-fips | 5.4.0-1069.73+fips2 | — |
| Ubuntu Pro FIPS-updates 20.04 LTS | linux-azure-fips | 5.4.0-1073.76+fips1 | — |
| Ubuntu Pro FIPS-updates 20.04 LTS | linux-gcp-fips | 5.4.0-1067.71~20.04.1 | — |
| Ubuntu Pro FIPS-updates 18.04 LTS | linux-aws-fips | 4.15.0-2030.31 | — |
| Ubuntu Pro FIPS-updates 18.04 LTS | linux-azure-fips | 4.15.0-2012.14 | — |
| Ubuntu Pro FIPS-updates 18.04 LTS | linux-fips | 4.15.0-1044.50 | — |
| Ubuntu Pro FIPS-updates 16.04 LTS | linux-fips | No fix yet | — |
| Ubuntu Pro 20.04 LTS | linux | 5.4.0-51.56 | LSN-0072-1 |
| Ubuntu Pro 20.04 LTS | linux-aws +1 | 5.4.0-1028.29 | LSN-0072-1 |
| Ubuntu Pro 20.04 LTS | linux-azure | 5.4.0-1031.32 | LSN-0072-1 |
| Ubuntu Pro 20.04 LTS | linux-azure-fde-5.15 | 5.15.0-1114.123~20.04.1 | — |
| Ubuntu Pro 18.04 LTS | linux | 4.15.0-121.123 | LSN-0072-1 |
| Ubuntu Pro 18.04 LTS | linux-aws | 4.15.0-1086.91 | LSN-0072-1 |
| Ubuntu Pro 18.04 LTS | linux-oem | 4.15.0-1099.109 | LSN-0072-1 |
| Ubuntu Pro 16.04 LTS | linux | 4.4.0-193.224 | LSN-0072-1 |
| Ubuntu Pro 16.04 LTS | linux-aws | 4.4.0-1117.131 | LSN-0072-1 |
| Ubuntu Pro 16.04 LTS | linux-kvm | No fix yet | — |
| Ubuntu Pro 14.04 LTS | linux +1 | No fix yet | — |
| Ubuntu Pro 14.04 LTS | linux-azure | 4.15.0-1098.109~14.04.1 | USN-4578-1 |
| Ubuntu Pro 14.04 LTS | linux-lts-xenial | 4.4.0-193.224~14.04.1 | LSN-0072-1 |
SUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES 15 SP2 | kernel-azure +2 | 5.3.18-18.24.1 | SUSE-SU-2020:3491-1 |
| SLES 15 SP2 | kernel-default-base | 5.3.18-24.34.1.9.11.2 | SUSE-SU-2020:3122-1 |
| SLES 15 SP2 | kernel-docs +5 | 5.3.18-24.34.1 | SUSE-SU-2020:3122-1 |
| SLES 15 SP1 | kernel-azure +2 | 4.12.14-8.52.1 | SUSE-SU-2020:3484-1 |
| SLES 15 SP1 | kernel-docs +5 | 4.12.14-197.67.1 | SUSE-SU-2020:3272-1 |
| SLES 15 | kernel-docs +6 | 4.12.14-150.63.1 | SUSE-SU-2020:3532-1 |
| SLES 12 SP5 | kernel-azure +2 | 4.12.14-16.34.1 | SUSE-SU-2020:3281-1 |
| SLES 12 SP5 | kernel-docs +4 | 4.12.14-122.51.2 | SUSE-SU-2020:3326-1 |
| SLES 12 SP4 | kernel-syms +2 | 4.12.14-95.65.1 | SUSE-SU-2020:3544-1 |
Show 14 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES for SAP 15 | kernel-docs +5 | 4.12.14-150.63.1 | SUSE-SU-2020:3532-1 |
| SLES for SAP 12 SP5 | kernel-azure +2 | 4.12.14-16.34.1 | SUSE-SU-2020:3281-1 |
| SLES for SAP 12 SP5 | kernel-syms +2 | 4.12.14-122.51.2 | SUSE-SU-2020:3326-1 |
| SLES for SAP 12 SP4 | kernel-syms +2 | 4.12.14-95.65.1 | SUSE-SU-2020:3544-1 |
| SLE Real Time 12 SP5 | kernel-rt +3 | 4.12.14-10.22.1 | SUSE-SU-2020:3512-1 |
| SLE Live Patching 15 SP2 | kernel-default | 5.3.18-24.34.1 | SUSE-SU-2020:3122-1 |
| SLE Live Patching 15 SP2 | kernel-livepatch-SLE15-SP2_Update_6 | 1-5.3.2 | SUSE-SU-2020:3122-1 |
| SLE Live Patching 15 SP1 | kernel-default | 4.12.14-197.67.1 | SUSE-SU-2020:3272-1 |
| SLE Live Patching 15 SP1 | kernel-livepatch-SLE15-SP1_Update_18 | 1-3.3.1 | SUSE-SU-2020:3272-1 |
| SLE Live Patching 15 | kernel-default | 4.12.14-150.63.1 | SUSE-SU-2020:3532-1 |
| SLE Live Patching 15 | kernel-livepatch-SLE15_Update_21 | 1-1.5.1 | SUSE-SU-2020:3532-1 |
| SLE Live Patching 12 SP5 | kernel-default | 4.12.14-122.51.2 | SUSE-SU-2020:3326-1 |
| SLE Live Patching 12 SP5 | kgraft-patch-SLE12-SP5_Update_12 | 1-8.5.2 | SUSE-SU-2020:3326-1 |
| SLE Live Patching 12 SP4 | kernel-default | 4.12.14-95.65.1 | SUSE-SU-2020:3544-1 |
| SLE Live Patching 12 SP4 | kgraft-patch-SLE12-SP4_Update_17 | 1-6.5.1 | SUSE-SU-2020:3544-1 |
| SLE HPC 15 | kernel-docs +5 | 4.12.14-150.63.1 | SUSE-SU-2020:3532-1 |
| SUSE Real Time Module 15 SP2 | kernel-rt +3 | 5.3.18-16.1 | SUSE-SU-2020:3522-1 |
| SUSE Real Time Module 15 SP1 | kernel-rt +3 | 4.12.14-14.41.2 | SUSE-SU-2020:3513-1 |
| SUSE OpenStack Cloud Crowbar 9 | kernel-syms +2 | 4.12.14-95.65.1 | SUSE-SU-2020:3544-1 |
| SUSE OpenStack Cloud 9 | kernel-syms +2 | 4.12.14-95.65.1 | SUSE-SU-2020:3544-1 |
openSUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| openSUSE Leap 15.2 | kernel-default-base | 5.3.18-lp152.50.1.lp152.8.10.1 | openSUSE-SU-2020:2112-1 |
| openSUSE Leap 15.2 | kernel-docs +8 | 5.3.18-lp152.50.1 | openSUSE-SU-2020:1906-1 |
| openSUSE Leap 15.2 | kernel-rt +3 | 5.3.18-lp152.3.5.1 | openSUSE-SU-2021:0242-1 |
Azure Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Azure Linux 2 (CBL-Mariner) | kernel | 5.10.78.1-1 | — |
Oracle Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Oracle Linux 7 | kernel-uek-container | 4.14.35-2047.501.0.el7 | ELSA-2021-9087, ELSA-2021-9086 |
| Oracle Linux 7 | kernel-uek-container-debug | 5.4.17-2036.104.4.el8 | ELSA-2021-9086 |
| Oracle Linux 7 | perf +10 | 4.14.35-2047.501.1.el7uek | ELSA-2021-9085, ELSA-2021-9084 |
Advisories 24
- USN-4578-1 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) · Sep 7, 2026
- USN-4576-1 linux, linux-aws, linux-aws-5.4, linux-azure, linux-azure-5.4, linux-gcp, linux-gcp-5.4, linux-hwe-5.4, linux-kvm, linux-oracle, linux-oracle-5.4, linux-raspi, linux-raspi-5.4 vulnerabilities Ubuntu Security Notices (USN) · Jun 3, 2026
- USN-4577-1 linux-hwe, linux-gke-5.0, linux-gke-5.3, linux-oem-osp1, linux-raspi2-5.3 vulnerabilities Ubuntu Security Notices (USN) · Jun 3, 2026
- LSN-0072-1 Kernel Live Patch Security Notice Ubuntu Security Notices (USN) · Jun 3, 2026
- openSUSE-SU-2021:0242-1 Security update for RT kernel SUSE / openSUSE Security Updates · Feb 4, 2026
- SUSE-SU-2020:3484-1 Security update for the Linux Kernel SUSE / openSUSE Security Updates · Feb 4, 2026
- SUSE-SU-2020:3522-1 Security update for the Linux Kernel SUSE / openSUSE Security Updates · Feb 4, 2026
- SUSE-SU-2020:3544-1 Security update for the Linux Kernel SUSE / openSUSE Security Updates · Feb 4, 2026
- SUSE-SU-2020:3491-1 Security update for the Linux Kernel SUSE / openSUSE Security Updates · Feb 4, 2026
- SUSE-SU-2020:3513-1 Security update for the Linux Kernel SUSE / openSUSE Security Updates · Feb 4, 2026
- SUSE-SU-2020:3532-1 Security update for the Linux Kernel SUSE / openSUSE Security Updates · Feb 4, 2026
- SUSE-SU-2020:3512-1 Security update for the Linux Kernel SUSE / openSUSE Security Updates · Feb 4, 2026
- SUSE-SU-2020:3326-1 Security update for the Linux Kernel SUSE / openSUSE Security Updates · Feb 4, 2026
- openSUSE-SU-2020:1906-1 Security update for the Linux Kernel SUSE / openSUSE Security Updates · Feb 4, 2026
- SUSE-SU-2020:3122-1 Security update for the Linux Kernel SUSE / openSUSE Security Updates · Feb 4, 2026
- SUSE-SU-2020:3281-1 Security update for the Linux Kernel SUSE / openSUSE Security Updates · Feb 4, 2026
- VDE-2025-053 Phoenix Contact: Multiple Vulnerabilities in PLCnext Firmware CERT@VDE · Jul 8, 2025
- openSUSE-SU-2020:2112-1 Security update for the Linux Kernel SUSE / openSUSE Security Updates · May 7, 2025
- SUSE-SU-2020:3272-1 Security update for the Linux Kernel SUSE / openSUSE Security Updates · May 2, 2025
- WID-SEC-2022-1762 Linux Kernel: Mehrere Schwachstellen BSI CERT-Bund (WID) · Jun 24, 2024
- ELSA-2021-9084 Important: Unbreakable Enterprise kernel security update (Oracle Linux 7) Oracle Linux Security Advisories (ELSA) · Mar 12, 2021
- ELSA-2021-9085 Important: Unbreakable Enterprise kernel security update (Oracle Linux 7) Oracle Linux Security Advisories (ELSA) · Mar 11, 2021
- ELSA-2021-9086 Important: Unbreakable Enterprise kernel-container security update (Oracle Linux 7) Oracle Linux Security Advisories (ELSA) · Mar 9, 2021
- ELSA-2021-9087 Important: Unbreakable Enterprise kernel-container security update (Oracle Linux 7) Oracle Linux Security Advisories (ELSA) · Mar 9, 2021
References
- https://ubuntu.com/USN-4576-1 vendor-advisory
- https://ubuntu.com/USN-4577-1 vendor-advisory
- https://ubuntu.com/USN-4578-1 vendor-advisory
- https://www.openwall.com/lists/oss-security/2020/10/14/2
- https://launchpad.net/bugs/1894980 vendor-advisory
- https://launchpad.net/bugs/1900141 vendor-advisory
- https://git.kernel.org/linus/56230d956739b9cb1cbde439d76227d77979a04d
- https://git.kernel.org/linus/48bd024b8a40d73ad6b086de2615738da0c7004f
- https://git.kernel.org/linus/05acefb4872dae89e772729efb194af754c877e8
- https://git.kernel.org/linus/d1d04ef8572bc8c22265057bd3d5a79f223f8f52
- https://git.kernel.org/linus/b6650dab404c701d7fe08a108b746542a934da84