Linux: patch a vulnerability with apt and dnf (Debian, RHEL)

A critical vulnerability has just been published in GnuTLS, the encryption library present across your whole estate, and it must be fixed within 24 hours. Except that the ERP vendor wrote to you this morning: their connector is only certified with the version of curl currently installed. Any curl upgrade stops invoicing. So you have to fix the vulnerability without letting curl move, on both halves of the estate, and be able to justify it to the auditor. A uniform estate only exists in training courses. Here you work with both families side by side, a server from the RHEL family and a Debian 12 container stuck at its 2023 version, and you learn to translate every operation from one to the other: dpkg and rpm to know, apt and dnf to change. First trap, the one that trips up most beginners: the package carries neither the command's name nor the same name from one distribution to the other. You will look at what an update would take with it before running it, fix only what is necessary and prove it by the installed version, not by the absence of errors. Then you will freeze curl on both sides, try to force the lock, and document the debt this freeze creates, with its lift date. That last point is the one you will be blamed for if it is missing. At the end, the machine and your sheet are checked, and the result counts for your ranking. Terminal in the browser, nothing to install.