CVE-2026-35371: id: pretty-print uses effective GID instead of effective UID for name lookup

The id utility in uutils coreutils exhibits incorrect behavior in its “pretty print” output when the real UID and effective UID differ. The implementation incorrectly uses the effective GID instead of the effective UID when performing a name lookup for the effective user. This results in misleading diagnostic output that can cause automated scripts or system administrators to make incorrect decisions regarding file permissions or access control.

Zellic finding 3.73. Reported in the Zellic uutils coreutils Program Security Assessment (for Canonical, Jan 2026), audited commit 3a07ffc5a9bd4c283e75afa548ba1f1957bad242.