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CVEs

CVE-2026-21509

exploited in the wild
CVSS
9.9
Reports
9
First seen
Jan 27
Last seen
Jun 2
Affected product

Microsoft Office 2016, 2019, 2021, 2024; Microsoft 365 Apps for Enterprise

Associated actors

APT28 ×2Black Axe ×1Contagious Interview ×1Diesel Vortex ×1Gamaredon ×1GrayBravo ×1HoneyMyte (Mustang Panda) ×1Kimwolf ×1Lotus Blossom ×1Mercenary Akula ×1NoName057(16) ×1Pawn Storm ×1PHALT#BLYX ×1Qilin ×1Salt Typhoon ×1Sandworm ×1Scattered Lapsus Hunters ×1Sednit ×1Storm-1516 ×1TGR-STA-1030 ×1

Recent reports

Critical

Gamaredon Exploits WinRAR to Deliver GammaWorm and GammaSteel Against Ukraine

The Hacker NewsHigh

Exploits and vulnerabilities in Q1 2026

Kaspersky SecurelistCritical

Pawn Storm Campaign Deploys PRISMEX, Targets Government and Critical Infrastructure Entities

Trend Micro ResearchCritical

Sednit reloaded: Advanced implant team returns with BeardShell and Covenant

ESET WeLiveSecurityHigh

CERT-EU Cyber Brief February 2026: APT28, China espionage, AI supply-chain attacks, Qilin ransomware

CERT-EU Threat IntelCritical

January 2026 CVE Landscape: 23 Critical Vulnerabilities, APT28 Exploits Microsoft Office Zero-Day

Recorded Future InsiktHigh

Microsoft Office Security Feature Bypass Vulnerability (CVE-2026-21509)

NICS TaiwanHigh

CERT-EU Cyber Brief January 2026 – Espionage, Ransomware, and Critical Vulnerabilities

CERT-EU Threat IntelHigh

Microsoft Office Security Restriction Bypass Vulnerability (CVE-2026-21509)

GovCERT.HK

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