cybersecurityzero-day vulnerabilitymicrosoft exchange serverdata breachcanada
Russian hackers exploit Exchange OWA zero-day for long-term mailbox access
July 29, 2026
Back to all postsRecent reports indicate that Russian state-sponsored hacking group Hafnium has been exploiting a zero-day vulnerability in Microsoft Exchange Server's Outlook Web Access (OWA). The flaw, tracked as CVE-2021-26855, allows attackers to gain access to mailbox contents and maintain long-term access by setting up their own web shell. This breach could lead to data theft, intellectual property loss, and potentially provide a foothold for further attacks within the targeted network. As Canadian SMBs heavily rely on digital communication, this vulnerability poses a significant threat to businesses operating in Canada. To mitigate risks, it's essential to apply Microsoft's security updates and patches immediately to secure Exchange Server environments.
Source: BleepingComputer
cybersecurityzero-day vulnerabilitymicrosoft exchange serverdata breachcanada
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