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Received — 9 July 2026 ⏭

Patch for Windows Defender 0-day could allow attackers to fill hard disk

✇Biz & IT - Ars Technica
By: Dan Goodin
9 July 2026 at 20:52

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.”

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Received — 9 June 2026 ⏭

Locked in heated rivalry with researcher, Microsoft fixes 0-day they disclosed

✇Biz & IT - Ars Technica
By: Dan Goodin
9 June 2026 at 20:56

Microsoft on Tuesday released fixes for two high-severity zero-days that were disclosed by a researcher who has been locked in a testy beef with the software giant.

Nightmare Eclipse, the pseudonym the researcher goes by, released a handful of high-severity vulnerabilities in recent months, making them zero-days that had the potential to be exploited in the wild. The researcher has said the disclosures, which included proof-of-concept code, came after Microsoft reneged on an arrangement the two made regarding vulnerabilities they had discussed.

Disclosure drama

“But someone violated our agreement and left me homeless with nothing,” Nightmare Eclipse wrote in March. “They knew this will happen and they still stabbed me in the back anyways, this is their decision not mine.”

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Received — 8 June 2026 ⏭

For the 2nd time in weeks, Microsoft packages laced with credential stealer

✇Biz & IT - Ars Technica
By: Dan Goodin
8 June 2026 at 18:34

Dozens of cryptographically verified open source packages from Microsoft were compromised late last week to add advanced credential-stealing code that was triggered when developers opened them in AI coding agents.

In all, multiple researchers said, 73 packages were flagged as malicious when automated systems on GitHub blocked them on the platform. Rather than noting they are malicious—and that developers who used AI agents to work with them should assume their systems are compromised—the Microsoft-owned GitHub said it disabled the packages “due to a violation of GitHub's terms of service.” The text went on to encourage the package owner to contact GitHub.

Devs: Assume compromise and proceed accordingly

It wasn’t until Monday that Microsoft even raised the possibility the packages were infected. In an email, the company stated: “We have temporarily removed some repositories as we investigate potential malicious content.”

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Received — 14 May 2026 ⏭

Zero-day exploit completely defeats default Windows 11 BitLocker protections

✇Biz & IT - Ars Technica
By: Dan Goodin
14 May 2026 at 18:32

A zero-day exploit circulating online allows people with physical access to a Windows 11 system to bypass default BitLocker protections and gain complete access to an encrypted drive within seconds.

The exploit, named YellowKey, was published earlier this week by a researcher who goes by the alias Nightmare-Eclipse. It reliably bypasses default Windows 11 deployments of BitLocker, the full-volume encryption protection Microsoft provides to make disk contents off-limits to anyone without the decryption key, which is stored in a secured piece of hardware known as a trusted platform module (TPM). BitLocker is a mandatory protection for many organizations, including those that contract with governments.

When one disk volume manipulates another

The core of the YellowKey exploit is a custom-made FsTx folder. Online documentation of this folder is hard to find. As explained later, the directory associated with the file fstx.dll appears to involve what Microsoft calls the transactional NTFS, which allows developers to have “transactional atomicity" for file operations in transactions with a single file, multiple files, or ones that span multiple sources.

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