util-linux libblkid DOS extended-partition overflow produces invalid partition metadata

util-linux is a random collection of Linux utilities. Before util-linux 2.41.4, `parse_dos_extended()` in `libblkid/src/partitions/dos.c` computes an extended-partition start sector with 32-bit addition and does not apply the extended-area bounds checks to the first two EBR entries. A local attacker who causes a crafted DOS extended-partition disk image or removable medium to be probed can wrap `cur_start + start` to sector zero and cause libblkid to report a false partition overlapping the MBR. This directly compromises the integrity of the reported partition metadata; disk modification or availability loss requires a separate downstream consumer to act on that metadata. This issue is fixed in 2.41.4.

Source published

14 Oct 2026 15:56:45 UTC

Source modified

15 Oct 2026 15:07:57 UTC

Observed here

23 Oct 2026 15:48:27 UTC

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CVSS 3.1 · 8.0 CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:L/I:H/A:H