Microsoft Office zero-day lets malicious documents slip past security checks


Microsoft issued an emergency patch for a high-severity zero-day vulnerability in Office that allows attackers to bypass document security checks and is being exploited in the wild via malicious files.

Microsoft pushed the emergency patch for the zero‑day, tracked as CVE-2026-21509, and classified it as a “Microsoft Office Security Feature Bypass Vulnerability” with a CVSS score of 7.8 out of 10. The flaw allows attackers to bypass Object Linking and Embedding (OLE) mitigations that are designed to block unsafe COM/OLE controls inside Office documents. This means a malicious attachment could infect a PC despite built-in protections.

Read more…
Source: Malwarebytes Labs


Sign up for the Cyber Security Review Newsletter
The latest cyber security news and insights delivered right to your inbox


Related:

  • Cisco warns of critical remote code execution flaws in its small business VPN routers

    February 5, 2021

    Cisco is warning customers using its small business routers to upgrade the firmware to fix flaws that could give remote attackers root level access to the devices. The critical flaws affect the Cisco Small Business RV160, RV160W, RV260, RV260P, and RV260W VPN Routers. These were the models Cisco recommended customers using unsupported small business routers to ...

  • Hacking group also used an IE zero-day against security researchers

    February 4, 2021

    An Internet Explorer zero-day vulnerability has been discovered used in recent North Korean attacks against security and vulnerability researchers. Last month, Google disclosed that the North Korean state-sponsored hacking group known as Lazarus was conducting social engineering attacks against security researchers. To perform their attacks, the threat actors created elaborate online ‘security researcher’ personas that would then ...

  • Google patches an actively exploited Chrome zero-day

    February 4, 2021

    Google has released today version 88.0.4324.150 of the Chrome browser for Windows, Mac, and Linux. Today’s release contains only one bugfix for a zero-day vulnerability that was exploited in the wild. The zero-day, which was assigned the identifier of CVE-2021-21148, was described as a “heap overflow” memory corruption bug in the V8 JavaScript engine. Google said the ...

  • Recent root-giving Sudo bug also impacts macOS

    February 3, 2021

    A British security researcher has discovered today that a recent security flaw in the Sudo app also impacts the macOS operating system, and not just Linux and BSD, as initially believed. The vulnerability, disclosed last week as CVE-2021-3156 (aka Baron Samedit) by security researchers from Qualys, impacts Sudo, an app that allows admins to delegate limited ...

  • US federal payroll agency hacked using SolarWinds software flaw

    February 2, 2021

    The FBI has discovered that the National Finance Center (NFC), a U.S. Department of Agriculture (USDA) federal payroll agency, was compromised by exploiting a SolarWinds Orion software flaw, according to a Reuters report. NFC provides human resources and payroll services to roughly 170 federal agencies and over 650,000 federal employees since 1973. The software vulnerability used to ...

  • SonicWall zero-day exploited in the wild

    February 1, 2021

    Cyber-security firm the NCC Group said on Sunday that it detected active exploitation attempts against a zero-day vulnerability in SonicWall networking devices. Details about the nature of the vulnerability have not been made public to prevent other threat actors from studying it and launching their own attacks. “We’ve seen it used by a single threat actor earlier ...