A logic error in the cut utility of uutils coreutils causes the utility to ignore the -s (only-delimited) flag when using the -z (null-terminated) and -d '' (empty delimiter) options together. The implementation incorrectly routes this specific combination through a specialized newline-delimiter code path that fails to check the record suppression status. Consequently, uutils cut emits the entire record plus a NUL byte instead of suppressing it. This divergence from GNU coreutils behavior creates a data integrity risk for automated pipelines that rely on cut -s to filter out undelimited data.

Affected: crates.io: uu_cut

`cut` routes `-z -d ''` through a special newline-delimiter path that ignores the `-s` only-delimited flag, emitting whole undelimited records (plus NUL) that should be suppressed. Pipelines relying on `cut -s` to drop undelimited records process data that should be filtered. ``` printf 'abc' | cut -z -d '' -s -f 1 | od -An -tx1 # GNU: no output ; uutils: 61 62 63 00 ```

--- _Zellic private finding (zellic-ext/coreutils-private PR #102). Reported in the Zellic *uutils coreutils Program Security Assessment* (for Canonical, Jan 2026), audited commit `3a07ffc5a9bd4c283e75afa548ba1f1957bad242`._

Affected: Ubuntu:24.04:LTS: rust-coreutils, Ubuntu:25.10: rust-coreutils

A logic error in the cut utility of uutils coreutils causes the utility to ignore the -s (only-delimited) flag when using the -z (null-terminated) and -d '' (empty delimiter) options together. The implementation incorrectly routes this specific combination through a specialized newline-delimiter code path that fails to check the record suppression status. Consequently, uutils cut emits the entire record plus a NUL byte instead of suppressing it. This divergence from GNU coreutils behavior creates a data integrity risk for automated pipelines that rely on cut -s to filter out undelimited data.