The securelevels implementation in FreeBSD 7.0 and earlier, OpenBSD up to 3.8, DragonFly up to 1.2, and Linux up to 2.6.15 allows root users to bypass immutable settings for files by mounting another filesystem that masks the immutable files while the system is running.
| Name | Vendor | Start Version | End Version |
|---|---|---|---|
| Dragonfly | Dragonfly | * | 1.2 (including) |
| Freebsd | Freebsd | * | 6.0 (including) |
| Freebsd | Freebsd | 7.0-current (including) | 7.0-current (including) |
| Linux_kernel | Linux | * | 2.6.15 (including) |
| Openbsd | Openbsd | * | 3.8 (including) |
| Linux-source-2.6.15 | Ubuntu | dapper | * |
| Linux-source-2.6.17 | Ubuntu | edgy | * |
| Linux-source-2.6.20 | Ubuntu | feisty | * |