A workspace proxy hostname prefix could be accepted as a valid proxy
access URL. An authenticated user could then be redirected to an
attacker-controlled domain with an application-connect API key in the
URL.
Require proxy access URL matches to have a hostname boundary after the
candidate hostname, allowing only the end of the URL, a port, or a
path.
Add regression coverage for proxy access URL and wildcard hostname
prefixes.
Refs: https://linear.app/codercom/issue/PLAT-384
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Co-authored-by: Bobby Ho <bobbidinho@gmail.com>