Unprivileged attackers can get root access on multiple major Linux distributions in default configurations by exploiting a newly disclosed local privilege escalation (LPE) vulnerability in the GNU C Library (glibc).
Lemmy (like its predecessors) is temporally arranged content. Think of it like having a discussion in a pub. Imagine bringing up a topic and someone said: but we discussed this 5 days ago, so we cannot discuss it now. Your obvious response would be: but I wasn't here five days ago. It's okay to repeat a conversation.
If you want more of a hierarchical structure, use wikipedia article conversations. Then each conversation only occurs once (ish). Not encouraging repeated conversation here will lead to slow content death -- like on StackOverflow.
If it upgrades some stuff, you were vulnerable, but you no longer are. If nothing upgrades, then you were already all good.
If you're doing that regularly, then your core system will generally be patched fixing almost all exploits in your core system, including this one. If not, you're vulnerable to this exploit and likely a whole bunch more stuff.
Edit: That's the simplest answer but if you're curious you can do a double-check for this particular vulnerability with apt changelog libc6 - generally speaking you won't see recent changes, but if a package has been recently updated you'll see a recent fix. So e.g. for this, I see the top change in the changelog is the fix from a couple weeks back:
glibc (2.36-9+deb12u4) bookworm-security; urgency=medium
* debian/patches/any/local-CVE-2023-6246.patch: Fix a heap buffer overflow
in __vsyslog_internal (CVE-2023-6246).
* debian/patches/any/local-CVE-2023-6779.patch: Fix an off-by-one heap
buffer overflow in __vsyslog_internal (CVE-2023-6779).
* debian/patches/any/local-CVE-2023-6780.patch: Fix an integer overflow in
__vsyslog_internal (CVE-2023-6780).
* debian/patches/any/local-qsort-memory-corruption.patch: Fix a memory
corruption in qsort() when using nontransitive comparison functions.
-- Aurelien Jarno Tue, 23 Jan 2024 21:57:06 +0100
If you are running apt then you are running debian or ubuntu which the article clearly states they are vulnerable.
but anyway I was asking how do I figure it out by myself