07:07 AM EDT, 07/23/2025 (MT Newswires) -- A Microsoft ( MSFT ) security patch released this month failed to fully fix a critical SharePoint vulnerability, potentially opening the door to a major cyber espionage campaign, Reuters reported Wednesday.

A spokesperson for the software company confirmed that its initial solution to the flaw, identified at a hacker competition in May, did not work, but added that it released further patches that resolved the issue, Reuters reported.

The flaw, dubbed ToolShell, was first discovered in May at a Berlin hacking contest and was exploited by suspected China-linked groups, including 'Linen Typhoon' and 'Violet Typhoon,' the Reuters report said.

The US National Nuclear Security Administration was among the agencies breached, though no classified data is believed to have been accessed, Bloomberg said Tuesday, citing a person with knowledge of the matter.

Microsoft ( MSFT ) did not immediately respond to MT Newswires' request for comment.

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