A patch Microsoft released on Wednesday to fix a zero-day vulnerability in its Defender security engine may cause Windows machines to write files large enough to completely consume available disk space, the researcher who discovered the flaw said.

RoguePlanet, tracked as CVE-2026-50656, came to public notice in June when NightmareEclipse, the pseudonymous name used by a researcher, disclosed it along with code for exploiting it. The vulnerability allows remote attackers to gain administrative control of Windows 10 and Windows 11 machines, even when real-time protection has been disabled. Over the past few months, the anonymous researcher has published a handful of other zero-days that have sent Microsoft scrambling to develop patches.

Writing files of unlimited size

Microsoft said Wednesday that it patched RoguePlanet with an update to the Microsoft Malware Protection Engine, which is used by the Defender antivirus app. The fix will automatically be downloaded and installed without users having to take any action. Wednesday’s update also includes “defense-in-depth updates to help improve security-related features.”

Read full article

Comments

A Linux vulnerability that allows untrusted virtual machines to gain root access to host machines is one of two high-severity flaws to surface this week in the open source operating system.

The vulnerability resides in KVM, which is, in essence, a virtual machine app included in the kernel of many Linux distributions. The vulnerability, tracked as CVE-2026-53359, allows guest virtual machines—such as those used in cloud platforms to isolate one user’s instance from the host OS and other user instances—to break out of that container.

Januscape: A threat to cloud platforms

The vulnerability affects KVM running on both AMD and Intel processors. It exploits bugs residing in the KVM guest-side, the portion of the VM that consists of only resources like the OS or drivers present in the guest VM, rather than resources present on the host machine. The threat went unnoticed in the Linux kernel for 16 years.

Read full article

Comments

In the brief history of AI security, the prompt injection has quickly become the top threat. Large language models are inherently unable to distinguish between legitimate instructions provided by users and malicious ones sneaked into emails, source code, and other third-party content the models are processing. This makes it trivial to surreptitiously inject malicious commands that the LLM readily follows.

With no way to enforce this crucial boundary between trusted and untrusted sources, AI engine developers are left to erect elaborate guardrails designed to mitigate the damage rather than solve the root cause.

To date, most prompt injections have fallen into a class known as push, in which each potential victim is targeted. For example, the adversary injects malicious instructions into an individual email or calendar invitation. Because the injection must then be sent (or pushed) to each specific target, the scale of the attack is limited, hampering mass exploits that hit the Internet at large.

Read full article

Comments

Researchers have found a never-before-seen piece of macOS malware that combines a series of clever tradecraft to infect Macs with stealthy, custom-developed credential-stealing code.

The malware is delivered in two stages. The first is distributed in a disk image that masquerades as Maccy, a clipboard manager for Macs. It’s compiled as AppleScript that is notable for the way it delivers the second stage. The malware is named PamStealer because the Rust-written infostealer uses the Pluggable Authentication Modules interface built into macOS to validate the target’s login password before sending it to an attacker-controlled server.

A quieter execution chain

The use of both disk image and AppleScript is common in malware for Macs. More unusual is the way PamStealer combines them to gain stealth. When the AppleScript is double-clicked, it’s opened in the macOS Script Editor, where the malicious functionality is buried deep within the file.

Read full article

Comments