Welcome to Blumira Briefings, your top headlines and trends for your security practice.

This week's episode:
- A critical and unpatched vulnerability, named "BlueHammer," has been publicly disclosed for Microsoft Windows operating systems, allowing a local attacker to gain elevated privileges up to a system-level account.
- A sophisticated espionage campaign, attributed to the Russian state-sponsored hacking group known as APT28 or Forest Blizzard, has been disrupted by U.S. authorities.
- A critical vulnerability, identified as CVE-2025-59528, in the Flowise low-code platform for building artificial intelligence (AI) workflows is currently being actively exploited by hackers

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Sources:
Experts published unpatched Windows zero-day BlueHammer
https://securityaffairs.com/190400/breaking-news/experts-published-unpatched-windows-zero-day-bluehammer.html
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Russia Hacked Routers to Steal Microsoft Office Tokens
https://krebsonsecurity.com/2026/04/russia-hacked-routers-to-steal-microsoft-office-tokens/
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Hackers exploit a critical Flowise flaw affecting thousands of AI workflows
https://www.csoonline.com/article/4155680/hackers-exploit-a-critical-flowise-flaw-affecting-thousands-of-ai-workflows.html