Russian Hackers Exploit Microsoft OWA Flaw to Keep Mailbox Access After Credential Rotation

The Russian threat actors recently linked to the exploitation of a now-patched vulnerability in Zimbra have been observed exploiting another vulnerability, this time in Microsoft Outlook Web Access (OWA), to target U.S. and European government entities, as well as the telecommunications, financial, hospitality, and aerospace sectors.

The activity, which began on July 22, 2026, involves the