Design flaws in issetugid()

jerm · August 4, 2026, 7:16am

gist.github.com

https://gist.github.com/nicowilliams/4daf74a3a0c86848d3cbd9d0cdb5e26e

issetugid-sadness.md

*Warning: work in progress.  Incomplete*

People who have been in security a long time (or even not that long) know that some inputs should be treated
as tainted.  For example, environment variables from a user should not be used in a
set-uid program, inputs from a different user should be validated, etc...
Traditionally we say that the environment of a set-uid program is *`tainted`* and
should not be used (or used with much care).

Therefore we want all set-uid/set-gid programs to treat their environment and user
inputs as tainted.

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Design flaws in issetugid()

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