Microsoft patched a critical heap buffer overflow in the Windows DNS Client. An attacker needs no account and no help from the person sitting at the machine to trigger it. Every Windows machine that performs DNS lookups is potentially in scope, and every Windows machine performs DNS lookups constantly.

The vulnerability is tracked as CVE-2026-41096 with a CVSS score of 9.8. It sits in a component called dnsapi.dll, the file that handles DNS lookups on every Windows machine. DNS, which stands for Domain Name System, is the system that translates domain names into IP addresses so computers know where to connect. Every time a browser loads a page, an application connects to a server, a VPN establishes, or Windows checks for updates, the system sends out a DNS query asking what IP address belongs to a given name. The DNS Client receives the answer, processes it, and passes it along.

MacSync is spreading through Google ads that lead directly to claude.ai. The installation guide there was written by Claude itself. One Terminal command and the malware is running, your credentials are gone, and your crypto wallet applications have been replaced.

Security researcher Berk Albayrak spotted an active version of this campaign on May 9, 2026 and posted his findings on X. Researcher g0njxa also published findings on X tracing the campaign infrastructure. BleepingComputer independently confirmed a second variant running on completely separate infrastructure.

GhostLock locks every shared file on any Windows network in minutes using nothing but a standard login, and every security tool watching stays completely silent. This has been possible for over 30 years. Microsoft is not going to patch this.

Security researcher Kim Dvash published the proof of concept in May 2026, after discovering the technique during a prior authorized red team engagement.

SMB is the protocol Windows uses to share files across a network. When a program opens a file over SMB, it tells Windows how it wants to share that file with other programs at the same time. Set that sharing mode to zero using a parameter called dwShareMode in the CreateFileW API call, and Windows grants an exclusive deny-share handle. While that handle is held open, every other process, user, or system trying to open the same file gets back one thing:

A backdoor called PamDOORa targets Linux systems through PAM and steals SSH credentials from every user who logs in. It leaves no trace in process lists, antivirus, or logs. When the security team connects via SSH to investigate, their credentials get stolen too.

When someone logs into a Linux server, the system runs PAM to check the password. PAM stands for Pluggable Authentication Modules, and it handles authentication for everything that requires a login: SSH, sudo, the login prompt. Instead of building that check into each program separately, Linux sends everything through PAM using configuration files stored in /etc/pam.d/, one file per service. The file for SSH is /etc/pam.d/sshd. It tells PAM which modules to run, in what order, and what to do when one fails.

A new Linux zero-day called Dirty Frag gives any local user full root access on every major Linux distribution, and right now no distribution has a patched kernel available. The researcher planned to give distributions until May 12 to prepare. Someone leaked the exploit five days early, and it went public before a single distribution had a fix ready.

Hyunwoo Kim (@v4bel) found both vulnerabilities and quietly reported them to the Linux kernel security team at the end of April, including working exploits and patches. The plan was to give Linux distributions until May 12 to prepare fixes before anything went public. On May 7, he told the group of distribution maintainers about it and set that five-day hold in motion. That same day, someone else published the exploit online. The agreement was clear: if that happened, everything would go public immediately. Kim released the full details within hours. Two CVEs have since been assigned: CVE-2026-43284 for the IPsec variant, which now has a patch in the kernel mainline, and CVE-2026-43500 for the RxRPC variant, which has no patch anywhere yet. How the exploit got out early is still unknown. The patch for the IPsec bug had been sitting on a public kernel mailing list since April 30, so someone paying close attention to kernel development could have spotted it there. Or someone inside the distribution group leaked it. Nobody knows.

Twelve critical vulnerabilities were just published for vm2, a Node.js security library that sits inside millions of applications. Three of them score a perfect 10 out of 10. The creator shut the project down in 2023 because it was too broken to fix, restarted it anyway in October 2025, and here we are.

The library is called vm2. When a platform lets users run their own code, that code needs somewhere to run where it cannot touch anything it should not touch. Not the files on the server, not the ability to run system commands, not connections to other services. That sealed-off space where code runs but cannot escape is called a sandbox. vm2 was the tool Node.js developers used to build one.

Google Chrome installed a 4 GB AI model on your machine without asking. The pitch is that it runs locally, keeping your data off Google’s servers. The AI button you actually see in your browser sends everything to Google anyway.

Privacy researcher Alexander Hanff found this during a routine web audit in late April and published his full analysis on 4 May 2026, two days ago. He had built a Chrome profile to run automated tests, the kind where software loads web pages in the background and measures what happens. The profile received no human input whatsoever: nobody moved the mouse, hit a key, or touched the address bar. Chrome just ran quietly in the background doing its thing.

Microsoft Edge loads every saved password into memory the moment the browser opens. They sit there in plain readable text for the entire session, even for sites that are never visited during that session. Microsoft’s official response: this is by design.

A security researcher who goes by @L1v1ng0ffTh3L4N decided to test every major Chromium-based browser to see how each one actually handles stored credentials while running. He went through them one by one. Edge was the only browser he found behaving this way. He took his findings to the BigBiteOfTech conference on April 29, presented them there with Palo Alto Networks Norway, and then posted a proof-of-concept video on May 4 that pulled in 5,900 responses within hours. He also put a small tool on GitHub called EdgeSavedPasswordsDumper so anyone could check this on their own machine.

Microsoft Defender deleted DigiCert root certificates from Windows machines worldwide and flagged them as Trojan:Win32/Cerdigent.A!dha. Those certificates tell your browser which websites to trust, and tell Windows which software is safe to run. DigiCert was hacked through a screensaver file in a customer support chat, Microsoft tried to respond, and Defender ended up deleting the very thing it was trying to protect.

DigiCert is a certificate authority. A certificate is what tells your browser that a website is real, and what tells Windows that software was actually built by the company whose name is on it. When you see a padlock in your browser, a certificate made that happen. When Windows decides whether to run a program without warning you, it checked a certificate. DigiCert issues more of those certificates than almost anyone else. When you log into your bank, check your email, or install software from a trusted vendor, there is a reasonable chance a DigiCert certificate was involved somewhere in that process.

Hashcat v7.1.2 has three unpatched vulnerabilities, all rated 9.8 out of 10. The tool that security professionals use to crack passwords can be used to crack the machine running it. The CVEs landed on May 1, 2026. There is still no patch.

Hashcat is the standard tool for recovering passwords from hashes. A hash is what a password looks like after a one-way scrambling algorithm runs over it. When a database leaks, the passwords do not come out as readable text. They come out as hashes, long strings of letters and numbers that look like gibberish. Hashcat works backwards. It takes guesses, runs the same algorithm over them, and checks whether the result matches a hash in the list. A single RTX 4090 can run through nearly 300 billion of those checks every second for the NTLM hash type used across Windows corporate networks. The tool has won the KoreLogic “Crack Me If You Can” 562901440119f978aa2b3ed1c1b6439a competition at DEF CON multiple times. Turns out, you can.