[BUG] npx does not preserve PATH environment variable correctly.

Is there an existing issue for this?

• I have searched the existing issues

This issue exists in the latest npm version

• I am using the latest npm

Current Behavior

npx appears to be inserting /usr/bin ahead of all other path entries, causing problems for version managers that depend on adding specific entries before more general system entries:

> npx --no-install bash -c "env | grep PATH"
GEM_PATH=/home/samuel/.gem/ruby/3.4.6:/home/samuel/.rubies/ruby-3.4.6/lib/ruby/gems/3.4.0
PATH=/usr/bin:/home/samuel/Developer/socketry/lively/examples/game-audio/node_modules/.bin:/home/samuel/Developer/socketry/lively/examples/node_modules/.bin:/home/samuel/Developer/socketry/lively/node_modules/.bin:/home/samuel/Developer/socketry/node_modules/.bin:/home/samuel/Developer/node_modules/.bin:/home/samuel/node_modules/.bin:/home/node_modules/.bin:/node_modules/.bin:/usr/lib/node_modules/npm/node_modules/@npmcli/run-script/lib/node-gyp-bin:/home/samuel/.gem/ruby/3.4.6/bin:/home/samuel/.rubies/ruby-3.4.6/lib/ruby/gems/3.4.0/bin:/home/samuel/.rubies/ruby-3.4.6/bin:/home/samuel/Developer/jruby/jruby/bin:/usr/local/bin:/usr/bin:/usr/bin/site_perl:/usr/bin/vendor_perl:/usr/bin/core_perl

> bash -c "env | grep PATH"
GEM_PATH=/home/samuel/.gem/ruby/3.4.6:/home/samuel/.rubies/ruby-3.4.6/lib/ruby/gems/3.4.0
PATH=/home/samuel/.gem/ruby/3.4.6/bin:/home/samuel/.rubies/ruby-3.4.6/lib/ruby/gems/3.4.0/bin:/home/samuel/.rubies/ruby-3.4.6/bin:/home/samuel/Developer/jruby/jruby/bin:/usr/local/bin:/usr/bin:/usr/bin/site_perl:/usr/bin/vendor_perl:/usr/bin/core_perl

Note that /usr/bin is inserted at the start of PATH when running under npx. But it's already listed later on.

Because of that, ruby is resolved differently:

> npx --no-install bash -c "which ruby"
/usr/bin/ruby

> bash -c "which ruby"
/home/samuel/.rubies/ruby-3.4.6/bin/ruby

Expected Behavior

npx should not add system paths to the PATH environment variable.

Steps To Reproduce

See the given commands.

Environment

• npm: 11.6.1
• Node.js: 24.8.0
• OS Name: Linux aiko 6.16.8-arch3-1 #1 SMP PREEMPT_DYNAMIC Mon, 22 Sep 2025 22:08:35 +0000 x86_64 GNU/Linux

Start with the npx --no-install command shown in the reproduction and trace how it constructs the child process PATH. Compare its output with the plain bash command, then verify that system paths are not inserted ahead of existing entries and that ruby resolves consistently. The issue names no source files or tests to run.