CVE 2019-11697

If the ALT and "a" keys are pressed when users receive an extension installation prompt, the extension will be installed without the install prompt delay that keeps the prompt visible in order for users to accept or decline the installation. A malicious web page could use this with spoofing on the page to trick users into installing a malicious extension. This vulnerability affects Firefox < 67.

See the CVE page on Mitre.org for more details.