The Mid Yorkshire NHS Hospitals Trust, which runs Pinderfields, Pontefract and Dewsbury Hospitals, were forced to respond to a “bug” that was found on its servers earlier this summer.
A meeting was told that the bug had been removed before causing any harm.
In a report to the trust’s board on Thursday, chief executive Martin Barkley said a “major threat” to the security of hospitals’ “infrastructure and systems”, had been detected by staff and that it affected 12 different IT servers.
Hospital bosses had become aware of it before it was flagged up to them by NHS Digital. The issue was promptly fixed.
However, the trust later described the problem as a “business as usual incident” and clarified that it had not been a cyber attack.
Heather Cook, the organisation’s associate director for digital services, said: “The trust received an alert from NHS Digital regarding vulnerable Windows software, which had the potential to disable core IT infrastructure.
“However, our digital services team had been notified of the vulnerability previously by Microsoft, who provided a quick solution to the threat in the form of a standard update.
“The swift response of all partners involved nullified any risk caused by this bug.
“This was a ‘business as usual’ incident and something that we as a trust protect ourselves from on an ongoing basis via frequent system updates and close contact with suppliers.”
In May 2017 a huge cyber attack affected hospitals across the country, eventually costing the NHS £92million.