CVE-2026-53613

01/Description

util-linux is a random collection of Linux utilities. In util-linux 2.17 through 2.41.6 and 2.42 through 2.42.3, and in 2.42.4 when the legacy `mount(2)` path is used without `/proc`, restricted non-root `mount` requests validate an `/etc/fstab` target before the mount operation re-resolves that pathname. A local low-privileged user authorized by an fstab `user` or `users` entry whose target has an attacker-writable ancestor can use `renameat2(RENAME_EXCHANGE)` to swap a path component and redirect an authorized mount to a root-owned location, such as mounting attacker-controlled content over `/etc/sudoers.d`, and thereby gain root privileges. Versions 2.41.5 and 2.42.2 pin targets for the new mount API, and 2.42.4 pins legacy targets through `/proc/self/fd`; the documented legacy fallback without `/proc` remains affected.

02/References10

• github.com/util-linux/util-linux/commit/0b010025a0e429bc80355c9…
• github.com/util-linux/util-linux/commit/0d3d55975aa3492c62fd345…
• github.com/util-linux/util-linux/commit/2c773f336134acf016e639a…
• github.com/util-linux/util-linux/commit/39fef62bf3226abb6bb018f…
• github.com/util-linux/util-linux/commit/472cc3fb2d4d47cca7aab2e…
• github.com/util-linux/util-linux/commit/646fb66603d10a7ac337e14…
• github.com/util-linux/util-linux/commit/708d1b3c51932dc5ba8082c…
• github.com/util-linux/util-linux/commit/78a860982e036f38fe9c0b3…
• github.com/util-linux/util-linux/commit/85d16b341f7232c9dbb4884…
• github.com/util-linux/util-linux/commit/a9508d216eb897797910278…