Microsoft today released software updates to plug nearly 200 security holes across its Windows operating systems and supported software, a record number of fixes for the company’s monthly Patch Tuesday cycle. Nearly three dozen of those bugs earned Microsoft’s most dire “critical” rating, and exploit code for at least three of the weaknesses is now publicly available.

The software giant said in a blog post last month that both its engineers and the security community are increasing using artificial intelligence tools to find bugs, meaning this month’s heavy Patch Tuesday may start to become the norm, said Satnam Narang, senior staff research engineer at Tenable.

“Some surveys put AI usage among security professionals generally at 90%, so it’s unsurprising that this volume of patches may be the norm,” Narang said. “Pandora’s proverbial box has been opened, and as more advanced AI models become available, we expect the norm to continue upward across the board, not just for Patch Tuesday.”

June’s zero-day bugs include CVE-2026-49160, a denial of service vulnerability affecting a range of web servers, including Microsoft Internet Information Services (IIS). Microsoft says the flaw was reported by OpenAI’s Codex.

Two of the zero-days addressed this month appear to stem from recent vulnerability disclosures by Nightmare Eclipse, the nickname chosen by a security researcher who has been dropping exploits for various Windows flaws. One of those, dubbed “GreenPlasma,” leverages an elevation of privilege weakness in the Windows Collaborative Translation Framework, the same framework patched today in CVE-2026-45586.

Nightmare Eclipse also last month released “YellowKey,” an exploit for a Windows BitLocker vulnerability that allows an attacker with physical access to view encrypted data, and CVE-2026-50507 is a patch for an elevation of privilege bug in BitLocker.

Microsoft received heavy blowback on social media last month after it said in a blog post that it was considering taking legal action against the security researcher. The company later clarified on Twitter/X that while it has no intention of pursuing legal actions against researchers, it would report them to authorities if they break the law. The advisories for CVE-2026-49160 and CVE-2026-50507 do not credit any researchers in the acknowledgement section, saying only that “Microsoft recognizes the efforts of those in the security community who help us protect customers through coordinated vulnerability disclosure.”

Nightmare Eclipse claims to be a former employee of Microsoft, although Microsoft has not responded to questions about this claim. Rapid7 notes that a recent blog post by Nightmare Eclipse included an image of Albert Wesker, a character from the Resident Evil video game series who formerly worked as a researcher for a technology company before going rogue.

Nightmare Eclipse has pledged to release even more zero-day exploits for Windows in what they called a “bone shattering” drop planned for July 14 (the same day as next month’s Patch Tuesday). Immediately following the release of Microsoft patches today, the researcher published an exploit for what they claimed was a zero-day bug in Windows Defender.

While 200 vulnerabilities may be a record for Patch Tuesday, the actual number of security flaws Microsoft addressed this month is far higher, said Rapid7’s Adam Barnett.

“So far this month, Microsoft has provided patches to address 360 browser vulnerabilities, which is an order of magnitude more than has been typical in any given month over the past few years,” Barnett wrote. “As usual, browser [flaws] are not included in the Patch Tuesday count above. Indeed, the vast, and presumably sustained, uptick in the number of browser vulnerabilities has led to Microsoft no longer enumerating Chromium CVEs in the Security Update Guide.”

Microsoft also patched a zero-day vulnerability in Visual Studio Code that allows attackers to steal GitHub tokens with a single click. The company was forced to push a stopgap fix for the flaw on June 3, after a researcher published instructions showing how to exploit it. The researcher said they opted not to work with Microsoft because of a recent experience wherein Redmond silently patched a flaw they reported without offering credit or recognition.

Microsoft battled its own internal zero-day emergencies last week, after at least 72 of the company’s public code repositories were infected with a variant of the Shai-Hulud worm. Researchers found that all of the affected packages were connected to Microsoft official Azure Durable Task SDK, which got hit by the same Shai-Hulud worm in May.

Other major software makers are also shipping outsized update bundles this month. Adobe has released updates to fix a massive number of critical vulnerabilities across a range of products, including Adobe Experience Manager, Acrobat Reader and Cold Fusion. On June 3, Google resolved a whopping 429 vulnerabilities in its latest Chrome browser update (Chrome automatically downloads updates but installing them usually requires a complete restart of the browser).

As ever, please consider backing up your data before applying operating system updates, and drop a note in the comments if you run into any problems with this month’s patches.

Further reading:

Microsoft’s Security Update Guide

Action1’s Patch Tuesday breakdown

SANS Internet Storm Center notes on Patch Tuesday

The Instagram accounts for the Obama White House and the Chief Master Sergeant of the U.S. Space Force were briefly defaced with pro-Iranian images and messages over the weekend, after instructions began circulating on Telegram showing how to trick Meta’s “AI support assistant” bot into resetting account passwords.

A screenshot from a video released on Telegram claiming to show how Meta’s AI customer support bot could be tricked into resetting a target’s password.

On May 31, word began to spread on several Telegram instant message channels that Meta’s AI bot would happily add an email address to an existing account as part of the bot’s standard password reset flow.

A video released on Telegram by pro-Iran hackers claimed to document a remarkably simple exploit that appears to have involved using a VPN connection with an IP address that is in or near the target’s usual hometown, requesting a password reset for the account, and then choosing to chat with Meta’s AI support assistant. From there, the video shows the attacker told the bot to link the account in question to a new email address, after which the bot dutifully sent that address a one-time code that allowed a password reset.

The Telegram account that posted the video also linked to screenshots of pro-Iran images, videos and messages that defaced the hacked Instagram accounts, saying hackers had used the exploit to hijack a number of valuable (read: short) Instagram account names that allegedly have a resale value of more than a half million dollars.

Meta has not responded to requests for comment on the video’s claims, but Meta’s Andy Stone said on Twitter/X that the issue had been resolved and that they were securing impacted accounts. The security blog thecybersecguru.com reports that Meta pushed an emergency patch over the weekend, and clarified that no back end database was breached.

“Instagram has notoriously poor human support infrastructure,” Cybersecguru wrote. “Recovering a locked account – especially a high-value one can take weeks of back-and-forth with an automated ticketing system. Meta’s solution was to deploy a conversational AI layer to handle common recovery workflows: relinking a lost email address, triggering a password reset, verifying account ownership. The assistant, presumably, was supposed to reduce friction for legitimate users stuck in account-access hell.”

Ian Goldin, a threat researcher at Lumen’s Black Lotus Labs, said we’re entering unchartered security territory as more large online platforms start allowing AI chatbots to handle sensitive account recovery requests. Just like human customer support employees can be social engineered into providing unauthorized access to someone’s account, AI bots are equally eager to help and vulnerable to persuasion and trickery, he said.

“AI chatbots create interesting new attack surface, and we’re likely going to see a lot more of these kinds of attacks,” Goldin said.

Securing your various online accounts means taking full advantage of the most secure form of multi-factor authentication (MFA) offered (such as a passkey or security key). In this case, even using the least robust form of MFA that Instagram offers — a one-time code sent via SMS — likely would have blocked the exploit: The hackers who released the video on Telegram said their exploit failed to work against any accounts that had MFA enabled.

Lawmakers in both houses of Congress are demanding answers from the U.S. Cybersecurity & Infrastructure Security Agency (CISA) after KrebsOnSecurity reported this week that a CISA contractor intentionally published AWS GovCloud keys and a vast trove of other agency secrets on a public GitHub account. The inquiry comes as CISA is still struggling to contain the breach and invalidate the leaked credentials.

On May 18, KrebsOnSecurity reported that a CISA contractor with administrative access to the agency’s code development platform had created a public GitHub profile called “Private-CISA” that included plaintext credentials to dozens of internal CISA systems. Experts who reviewed the exposed secrets said the commit logs for the code repository showed the CISA contractor disabled GitHub’s built-in protection against publishing sensitive credentials in public repos.

CISA acknowledged the leak but has not responded to questions about the duration of the data exposure. However, experts who reviewed the now-defunct Private-CISA archive said it was originally created in November 2025, and that it exhibits a pattern consistent with an individual operator using the repository as a working scratchpad or synchronization mechanism rather than a curated project repository.

In a written statement, CISA said “there is no indication that any sensitive data was compromised as a result of the incident.” But in a May 19 a letter (PDF) to CISA’s Acting Director Nick Andersen, Sen. Maggie Hassan (D-NH) said the credential leak raises serious questions about how such a security lapse could occur at the very agency charged with helping to prevent cyber breaches.

“This reporting raises serious concerns regarding CISA’s internal policies and procedures at a time of significant cybersecurity threats against U.S. critical infrastructure,” Sen. Hassan wrote.

A May 19 letter from Sen. Margaret Hassan (D-NH) to the acting director of CISA demanded answers to a dozen questions about the breach.

Sen. Hassan noted that the incident occurred against the backdrop of major disruptions internally at CISA, which lost more than a third of it workforce and almost all of its senior leaders after the Trump administration forced a series of early retirements, buyouts, and resignations across the agency’s various divisions.

Rep. Bennie Thompson (D-MS), the ranking member on the House Homeland Security Committee, echoed the senator’s concerns.

“We are concerned that this incident reflects a diminished security culture and/or an inability for CISA to adequately manage its contract support,” Thompson wrote in a May 19 letter to the acting CISA chief that was co-signed by Rep. Delia Ramirez (D-Ill), the ranking member of the panel’s Subcommittee on Cybersecurity and Infrastructure Protection. “It’s no secret that our adversaries — like China, Russia, and Iran — seek to gain access to and persistence on federal networks. The files contained in the ‘Private-CISA’ repository provided the information, access, and roadmap to do just that.”

KrebsOnSecurity has learned that more a week after CISA was first notified of the data leak by the security firm GitGuardian, the agency is still working to invalidate and replace many of the exposed keys and secrets.

On May 20, KrebsOnSecurity heard from Dylan Ayrey, the creator of TruffleHog, an open-source tool for discovering private keys and other secrets buried in code hosted at GitHub and other public platforms. Ayrey said CISA still hadn’t invalidated an RSA private key exposed in the Private-CISA repo that granted access to a GitHub app which is owned by the CISA enterprise account and installed on the CISA-IT GitHub organization with full access to all code repositories.

“An attacker with this key can read source code from every repository in the CISA-IT organization, including private repos, register rogue self-hosted runners to hijack CI/CD pipelines and access repository secrets, and modify repository admin settings including branch protection rules, webhooks, and deploy keys,” Ayrey told KrebsOnSecurity. CI/CD stands for Continuous Integration and Continuous Delivery, and it refers to a set of practices used to automate the building, testing and deployment of software.

KrebsOnSecurity notified CISA about Ayrey’s findings on May 20. Ayrey said CISA appears to have invalidated the exposed RSA private key sometime after that notification. But he noted that CISA still hasn’t rotated leaked credentials tied to other critical security technologies that are deployed across the agency’s technology portfolio (KrebsOnSecurity is not naming those technologies publicly for the time being).

CISA responded with a brief written statement in response to questions about Ayrey’s findings, saying “CISA is actively responding and coordinating with the appropriate parties and vendors to ensure any identified leaked credentials are rotated and rendered invalid and will continue to take appropriate steps to protect the security of our systems.”

Ayrey said his company Truffle Security monitors GitHub and a number of other code platforms for exposed keys, and attempts to alert affected accounts to the sensitive data exposure(s). They can do this easily on GitHub because the platform publishes a live feed which includes a record of all commits and changes to public code repositories. But he said cybercriminal actors also monitor these public feeds, and are often quick to pounce on API or SSH keys that get inadvertently published in code commits.

The Private-CISA GitHub repo exposed dozens of plaintext credentials to important CISA GovCloud resources.

In practical terms, it is likely that cybercrime groups or foreign adversaries also noticed the publication of these CISA secrets, the most egregious of which appears to have happened in late April 2026, Ayrey said.

“We monitor that firehose of data for keys, and we have tools to try to figure out whose they are,” he said. “We have evidence attackers monitor that firehose as well. Anyone monitoring GitHub events could be sitting on this information.”

James Wilson, the enterprise technology editor for the Risky Business security podcast, said organizations using GitHub to manage code projects can set top-down policies that prevent employees from disabling GitHub’s protections against publishing secret keys and credentials. But Wilson’s co-host Adam Boileau said it’s not clear that any technology could stop employees from opening their own personal GitHub account and using it to store sensitive and proprietary information.

“Ultimately, this is a thing you can’t solve with a technical control,” Boileau said on this week’s podcast. “This is a human problem where you’ve hired a contractor to do this work and they have decided of their own volition to use GitHub to synchronize content from a work machine to a home machine. I don’t know what technical controls you could put in place given that this is being done presumably outside of anything CISA managed or even had visibility on.”

Update, 3:05 p.m. ET: Added statement from CISA. Corrected a date in the story (Truffle Security said it found the repo gained some of its most sensitive secrets in late April 2026, not 2025).