A report submitted to the council's adult performance and review panel on Thursday, November 14 said there has been a rise in incidents regarding the security of sensitive passwords and confidential post.
It also said that post has been sent to the wrong addresses, unauthorised people have accessed buildings, and laptops and mobile phones containing sensitive information have gone missing.
The council apologised to Hampshire County Council after a confidential package it sent to Hampshire was reported lost on September 26.
The Royal Borough said that some of the lapses have happened during the council's transition to 'Smarter Working'. It says Smarter Working allows staff more freedom to work from various offices and at home.
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The Met Office has issued a yellow alert for Windsor and Maidenhead, Slough and Wokingham, warning that rain moving eastwards across the south of the country may turn to snow in some places.