LastPass addon has been blocked for your protection.

Why was it blocked?
LastPass have announced there are security issues that would allow a malicious website to perform some actions (e.g. deleting passwords) without the user's knowledge. Beta versions 4.0 to 4.1.20a of their add-on that were available from addons.mozilla.org are affected and Lastpass also distributed these versions direct from their website.
Who is affected?
All users who install affected versions of this add-on - beta versions 4.0 to 4.1.20a from addons.mozilla.org or lastpass.com.
What does this mean?

The problematic add-on or plugin will be automatically disabled and no longer usable.

When Mozilla becomes aware of add-ons, plugins, or other third-party software that seriously compromises Firefox security, stability, or performance and meets certain criteria, the software may be blocked from general use. For more information, please read this support article.