Via the Steam Store:
An update has been released for Portal 2.
- Fix for a potential remote code execution exploit. Thanks to HackerOne for the report.
🐧 Play games on Linux? Help us by confirming which games work for you!
Portal 2 update for June 5, 2018
View all patches · Build 2833606 · Last edited August 11, 2018 – 09:06:01 UTC by 
Wendy