In RDoc 3.11 through 6.x before 6.3.1, as distributed with Ruby through 3.0.1, it is possible to execute arbitrary code via | and tags in a filename.
Exploitability
AV:LAC:HPR:LUI:NScope
S:UImpact
C:HI:HA:H7/CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H