Internet Explorer CVE-2020-0674: The Zero-Day Advisory That Opened 2020
On 17 January 2020, Microsoft published ADV200001, a rare out-of-band advisory for CVE-2020-0674, a remote code execution flaw in the scripting engine used by Internet Explorer 9 and 11 that the company confirmed was being exploited in limited targeted attacks. There was no patch yet, only mitigations and workarounds, and defenders spent nearly a month exposed until the 11 February 2020 cumulative update shipped the fix. This piece reconstructs the advisory, the memory-corruption mechanics in the script engine, why IE was still a live attack surface in 2020, and what the episode taught about mitigations-first disclosure.