Several technology companies have urged the public to reset their passwords amid fears of a major security problem with a product used to protect people's personal data.
The Heartbleed bug affects OpenSSL, which many companies use to protect sensitive information, including people's password.
A small padlock icon appears on websites using OpenSSL to reassure users, but the loophole in the programme could have left it open to exploitation by hackers.
Blogging platform Tumblr posted a public notice about the bug, advising users to "take some time to change your passwords everywhere - especially your high-security services like email, file storage, and banking".
Finnish security company Codenomicon also said it would be "a good idea" to change potentially vulnerable passwords.
More top news
A woman with amnesia has been reunited with her family in the US after her nephew spotted an appeal to help identify her on TV.
MPs could be asked to authorise airstrikes against IS in Syria in the wake of the Tunisia massacre, the defence secretary has suggested.
Cooler temperatures are forecast after thunderstorms and heavy downpours hit parts of Britain after the hottest July day on record.