Firefox 13's new thumbnail tab view could reveal sensitive private data, after Mozilla's latest browser was found to take "snapshots of the user's HTTPS session content."

Users have warned that SSL-protected websites --- such as online banking pages and web-mail services --- can reveal account numbers and email subject lines as they are 'snapshotted' and displayed in the browser's new tab page.

Mozilla admitted there was a "concern" with the browser's privacy, which was released on June 5, and said there would be a fix "in a future version of Firefox".

"Mozilla remains resolute in its commitment to privacy and user control. The new tab thumbnail feature within Firefox does not transmit nor store personal information outside the user's direct control," the browser maker said in an emailed statement.

Mozilla said that the thumbnails presented in tab view are based on the user's browsing history, and can be deleted from the browsing history at any time. Users can also use private browsing mode to prevent the recording of data.

Other browsers have similar features --- such as Chrome's tab view, and Opera's "speed dial" --- and the issue is certainly not new.

The Guardian dubbed Chrome a "security nightmare," as other users could see see similar private data in its tab screen view, among other highlighted issues. Firefox's thumbnails are far bigger and therefore pose a more significant problem --- while Chrome's thumbnails are far smaller and fixed in size.

Image credit: CNET. Article source: The Register.

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