Extension update checks
Adblock Plus for Firefox allows you to send issue reports to be temporarily stored on AdblockPlus.org domain. These reports contain information required to investigate the issue including Adblock Plus version, browser version, address of the web page where the problem is visible, blockable items on this web page, matching filters and active subscriptions. Parameter values are removed from all transmitted addresses to avoid unintentionally leaking private information. It is also possible to provide additional information, which may be privacy-sensitive:
Website screenshot provides a scaled-down and color-reduced version of the page viewed. It is possible to remove particularly sensitive sections of the page before the report is sent. Email address is only used to request more information or to update the user on the issue. List of installed extensions is necessary for the investigation of conflicts with other extensions.
The processed reports can only be accessed by somebody who knows their unique address. These addresses are only shared with the maintainers of the filter subscriptions mentioned in the report and are unlikely to be found by others unless a link is provided. All reports and their associated data are automatically removed after 30 days.
Further AdblockPlus.org website requests
Adblock Plus stores some data in the Firefox profile on your computer. Adblock Plus never transmits this data to any servers, but other extensions and services, such as Firefox Sync, may do so. Most of the data (your preferences, filter subscriptions and custom filters) is unobjectionable privacy-wise. However, filter hit statistics and recent issue reports could be used to reconstruct your browsing history. Adblock Plus treats this information identically to how history data is treated by the browser: this data isn't stored if you are using Private Browsing mode and is removed if you choose to clear your browsing history.