Notable before 1.9.0-beta.8 doesn't effectively prevent the opening of executable files when clicking on a link. There is improper validation of the file URI scheme. A hyperlink to an SMB share could lead to execution of an arbitrary program (or theft of NTLM credentials via an SMB relay attack, because the application resolves UNC paths).

Notable v1.8.4 does not filter text editing, allowing attackers to execute arbitrary code via a crafted payload injected into the Title text field.

Notable 1.8.4 allows XSS via crafted Markdown text, with resultant remote code execution (because nodeIntegration in webPreferences is true).