New critical remote code execution vulnerabilities in Microsoft's enterprise Exchange Server have been discovered, and the Australian Cyber Security Centre (ACSC) is urging users to apply the patches for them as soon as possible to prevent systems compromises.
The vulnerabilities are easy to exploit, do not require any user interaction, and affect Exchange Server 2013, 2016 and 2019.
Exchange Server 2010 is not affected by the vulnerabilities.
ACSC said the vulnerabilities can be exploited to gain and persist access to Exchange Server deployments.
The government cyber security agency warned that the earlier set of patches released by Microsoft last month for Hafnium do not take care of the new vulnerabilities.
Microsoft was forced to release a set of out-of-band security patches in March, after a nation-state threat actor, said to be Chinese, was found exploiting vulnerable Exchange Server installations.
ACSC said that a large number of Australian organisations have not patched vulnerable versions of Exchange Server, and urges these to do so as soon as possible.
Failing to patch could put the organisations at risk of ransomware criminals, ACSC warned.