PrintNightmare
CVE-2021-34527 — RCE + LPE in Windows Print Spooler. Accidentally leaked by researchers before Microsoft patched it.
Disclosed June-July 2021 in a chaotic mess: separate researchers thought a different bug had been patched, accidentally published a PoC. Multiple patches required (initial fix was incomplete). Made Microsoft eventually disable inbound spooler by default in Windows 11 22H2. Same family: SpoolFool (2022), various follow-on bugs.