According to a security bulletin published yesterday by Adobe, all versions of Flash older than 21.0.0.182 running on Windows are vulnerable. The specific vulnerability involved — designated CVE-2016-1019 — is flagged as Critical, and could allow an attacker to crash or take over control of targeted Windows systems.

Adobe says that Flash 21.0.0.182 contains a mitigation that protects it from this vulnerability, so if you use Flash, and you’re not already running 21.0.0.182 or newer, you should install it ASAP.

Adobe is working on a more comprehensive fix for this vulnerability and plans to release another new version of Flash in the next day or so.