Description
An issue was discovered in the Linux kernel 4.18 through 5.6.11 when unprivileged user namespaces are allowed. A user can create their own PID namespace, and mount a FUSE filesystem. Upon interaction with this FUSE filesystem, if the userspace component is terminated via a kill of the PID namespace's pid 1, it will result in a hung task, and resources being permanently locked up until system reboot. This can result in resource exhaustion.
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 | No fix yet | — |
| Debian 13 | linux | No fix yet | — |
| Debian 12 | linux | No fix yet | — |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu Nvidia-BlueField 24.04 LTS | linux-bluefield | No fix yet | — |
| Ubuntu Nvidia-BlueField 22.04 LTS | linux-bluefield | No fix yet | — |
| Ubuntu 26.10 | linux +8 | No fix yet | — |
| Ubuntu 26.04 LTS | linux +14 | No fix yet | — |
| Ubuntu 25.10 | linux +8 | No fix yet | — |
Show 20 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 24.04 LTS | linux +53 | No fix yet | — |
| Ubuntu 22.04 LTS | linux +59 | No fix yet | — |
| Ubuntu 20.04 LTS | linux-gke +27 | No fix yet | — |
| Ubuntu 18.04 LTS | linux-gcp +15 | No fix yet | — |
| Ubuntu 16.04 LTS | linux-hwe-edge | No fix yet | — |
| Ubuntu Pro Realtime 24.04 LTS | linux-realtime +3 | No fix yet | — |
| Ubuntu Pro Realtime 22.04 LTS | linux-realtime +2 | No fix yet | — |
| Ubuntu Pro FIPS 20.04 LTS | linux-fips +3 | 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 24.04 LTS | linux-fips +3 | No fix yet | — |
| Ubuntu Pro FIPS-updates 22.04 LTS | linux-fips +3 | No fix yet | — |
| Ubuntu Pro FIPS-updates 20.04 LTS | linux-fips +3 | No fix yet | — |
| Ubuntu Pro FIPS-updates 18.04 LTS | linux-fips +3 | No fix yet | — |
| Ubuntu Pro FIPS-updates 16.04 LTS | linux-fips | No fix yet | — |
| Ubuntu Pro FIPS-preview 22.04 LTS | linux-fips +3 | No fix yet | — |
| Ubuntu Pro 20.04 LTS | linux +21 | No fix yet | — |
| Ubuntu Pro 18.04 LTS | linux +12 | No fix yet | — |
| Ubuntu Pro 16.04 LTS | linux +7 | No fix yet | — |
| Ubuntu Pro 14.04 LTS | linux +3 | No fix yet | — |
Advisories 1
- WID-SEC-2022-1614 Linux Kernel: Mehrere Schwachstellen BSI CERT-Bund (WID) · Dec 9, 2025