Not content with broken Windows updates, Microsoft has disclosed two problems with Defender for Endpoint on Linux – one that could disable the security service after a reboot, and another that prevents updates on FIPS-enabled Red Hat Enterprise Linux 8 and 9. The more serious problem affected versions 101.26042.0000 through 101.26042.0009 across all supported Linux operating systems. After an upgrade or reinstall followed by a reboot, "the Defender service might be disabled on some devices," according to Microsoft. "If you use Defender for Servers (Plan 1 or 2) with Defender for Cloud and have the MDE [Microsoft Defender Endpoint] integration enabled, automatic updates for the MDE.Linux extension are enabled by default, which means your machines could have received an affected version automatically," it explained. "If an affected version was installed, the issue might impact active protection on rebooted devices until remediation steps are taken." Microsoft did not specify what caused Defender to become disabled, but anything that could knock out endpoint protection will give administrators sweaty palms. A separate problem affected RHEL 8 and 9 systems running in FIPS mode: the 101.26042.x update could fail to install, leaving devices on their previous version. FIPS refers to US Federal Information Processing Standards, which in this context impose requirements on the cryptography used by government and other regulated systems. Although Microsoft's alert did not mention an available update, its release notes direct users affected by the disabled-service bug to build 101.26042.0011. The separate FIPS installation problem is fixed in version 101.26052.0011 and later. Microsoft Defender for Endpoint on Linux protects server workloads on-premises and in the cloud. According to Microsoft, "it helps you prevent, detect, investigate, and respond to advanced threats with unified visibility through the Microsoft Defender portal." Other endpoint security platforms are available, but where an organization has gone all-in with Microsoft, the unified management offered by Defender for Endpoint on Linux can be difficult to resist. Microsoft has an unfortunate habit of shipping broken updates for its flagship operating system, Windows. An update that breaks software specifically designed to protect a device takes things to another level, particularly given the relentless rise in attacks and the need to both fend them off and monitor activity. Hence the appeal of unified visibility through the Microsoft Defender portal. However, an update that could leave Defender disabled after a reboot – while also refusing to install on some security-hardened systems – is less than ideal. ®

Kremlin cyber goons have been breaking into government and commercial networks for at least a year by exploiting a Zimbra bug with a novel twist on Russia’s usual phishing expeditions: this attack occurs as soon as the victim looks at an email, with no need to even click on a link or open a file. These attacks have been ongoing since July 2025, according to a whopping 27 US, UK, and other international government agencies, which attribute the intrusions to a group they track as Laundry Bear, aka Void Blizzard. “Laundry Bear’s targeting is almost certainly to gather sensitive information for the Russian Federation, with these actors primarily focusing on the covert acquisition of email data,” according to the joint security alert. The Russians’ latest campaign targets CVE-2025-66376, a cross-site scripting (XSS) vulnerability in the Zimbra web-based email and collaboration suite that was patched in November 2025 – but Moscow's attackers began exploiting it long before then. This type of vulnerability allows attackers to inject malicious JavaScript into web pages viewed by the victim. In this case, the phishing bears abused the security hole in the Zimbra Collaboration Suite by sending malware-laden HTML email messages to target Western organizations. Targeted orgs include those in the defense industrial base, federal and local governments, education, energy, law enforcement, media, non-governmental organizations, and technology sectors. Some of the email addresses used in this campaign include ivanka.zurabishvili@proton[.]me, zmul1@buildandconsulting[.]com, garrysmithme@pinmx[.]net, and hostingclient@pinmx[.]net, we’re told. The attack doesn’t require any user interaction other than viewing the malicious email, and once that happens, the attackers get to work exfiltrating a ton of data. This includes the victims’ last 90 days of email communications, email addresses and passwords, the organizations’ email directories such as global address lists, two-factor authentication tokens, and newly created application passcodes. Then the attackers use these stolen credentials to maintain access to the victims’ email, modifying account preferences and collecting authentication information. Laundry Bear stores the stolen goods on an unattributable virtual private server (VPS) running its custom “Flowerbed” collection framework. Flowerbed is a Python project that uses Docker for containerization. “The simplistic Flowerbed codebase has indications that artificial intelligence (AI) played a role in its development,” the government agencies noted. The 31-page security alert includes an extensive indicators of compromise (IOC) section, which organizations should review to identify individuals compromised by the campaign. Also, the agencies recommend minimizing employees’ use of the ZCS webmail client until their organizations update to a patched version that is not vulnerable to CVE-2025-66376. ®

Cisco today issued a fix for a Catalyst SD-WAN Manager bug that attackers have already spotted and exploited to get root privileges, according to both the networking vendor and the feds. The vulnerability, tracked as CVE-2026-20262, is in the web UI of Cisco Catalyst SD-WAN Manager, and exists because the software is not properly validating user-supplied input during a file upload process. “An attacker could exploit this vulnerability by sending a crafted HTTP request to an affected API endpoint of the affected system,” the vendor warned in a Monday security advisory. “A successful exploit could allow the attacker to create or overwrite any file on the underlying operating system. This file could later be used to elevate to root.” There is one caveat: to exploit this bug, the attacker must have valid credentials with at least a lower-privileged, single-task user account. That probably explains the medium-severity, 6.8 CVSS rating for this bug. Still, valid credentials aren’t hard to come by these days, and considering this CVE is already under attack, we know someone had some success. “In June 2026, the Cisco PSIRT became aware of limited exploitation of this vulnerability,” the security alert said. “Cisco continues to strongly recommend that customers upgrade to a fixed software release to remediate this vulnerability.” The flaw affects all deployment types, regardless of device configuration. There are no workarounds, but upgrading to a fixed software version will patch the flaw. Also on Monday, the US Cybersecurity and Infrastructure Security Agency (CISA) added CVE-2026-20262 to its Known Exploited Vulnerabilities catalog, citing “evidence of active exploitation.” America’s lead cyber-defense agency also set a two-week deadline for all federal agencies to apply the patch. This latest Cisco SD-WAN bug under attack comes less than two weeks after Switchzilla warned that a high-severity vulnerability in Catalyst SD-WAN Manager vulnerability (CVE-2026-20245) was under active exploitation. At the time of disclosure, this SD-WAN vuln did not have a fix. Cisco issued an advisory for that zero-day on June 4, and finally released patches for all affected versions on June 12. This is the eighth Cisco SD-WAN bug to be listed in CISA’s Known Exploited Vulnerabilities catalog so far this year.®

It's patch time for Ivanti customers again after the security shop disclosed another two critical vulnerabilities in one of its products. Both bugs affect Ivanti Sentry, a mobile gateway that forms part of its broader unified endpoint management platform. The first and worst of the two is CVE-2026-10520 (10.0), a max-severity vulnerability that allows a remote, unauthenticated attacker to execute code with root privileges. Flaws that allow root-level code execution without authentication are about as bad as vulnerabilities get, which explains the perfect-10 rating. The only saving grace is that, by the vendor's reckoning, no one has successfully exploited it in the wild… yet. Public disclosures tend to start a figurative countdown timer when it comes to attackers exploiting bugs, and although Ivanti gave little away about CVE-2026-10520 in its advisory, other researchers have already published breakdowns of the patch, offering clues as to how unpatched systems could still be attacked. According to watchTowr, the vulnerability stemmed from an exposed API running under Apache Tomcat. An attacker could feed the API a specially crafted message, which is parsed as a MICS configuration command and executed by the backend handler with root privileges. It looks like Ivanti fixed this by preventing this attacker-supplied string from being accepted, replacing it with a single, hard-coded command. It also updated the Apache configuration rules to block unauthenticated access to the affected endpoint. The second critical Ivanti Sentry vulnerability is tracked as CVE-2026-10523, and is scarcely less serious, carrying a near-maximum 9.9 CVSS. The authentication bypass bug allows remote, unauthenticated attackers to create admin accounts, granting themselves top privileges on an affected system. Customers are advised to address both security flaws immediately. They can upgrade to versions 10.5.2, 10.6.2, or 10.7.1. Ivanti's disclosure this week comes after it fixed two separate critical vulnerabilities affecting its Endpoint Manager Mobile (EPMM) in January. The bugs were both handed 9.8 CVSS scores and were exploited as zero-days. Even the Dutch data protection authority reported itself to parliament after attackers breached it as part of the pre-patch exploits. ®

Microsoft set a record with its June Patch Tuesday release, addressing 206 CVEs across its products and shipping fixes for them, with 38 deemed critical and the rest important. Three are listed as publicly known, but none (so far) have been exploited in the wild. We have no idea how many of these June bugs were uncovered using AI tools. Unlike last month’s patching event, when Redmond disclosed its agentic bug-hunting system found 16 of the 137 vulnerabilities, there’s no word on any AI assists for new releases. Still, it’s safe to assume AI played a major role. As Tom Gallagher, VP of engineering at Microsoft Security Response Center, said about May's Patch Tuesday with a whopping 30 critical flaws: “We expect releases to continue trending larger for some time.” June’s Patch Tuesday proved Gallagher correct, surpassing May in both overall volume and critical bugs. “I’ve been counting CVEs on Patch Tuesday since 2017, and this is by far the largest monthly release in that time,” Zero Day Initiative’s bug hunter in chief Dustin Childs said in his review. “It is extraordinary that Microsoft can produce so many patches in a single month, but it does raise concerns,” he added, asking, as we did: How many were found via AI? And: “How many patches were generated using AI to assist in coding or testing? What quality issues may exist in these patches? And likely most importantly, is this the new normal?” Childs noted that May and April also saw mega releases. “Should sysadmins adjust their processes for prioritization and patch deployment based on this new volume of updates? Unfortunately, Microsoft is not providing those answers right now,” he wrote, adding in this fun fact: “The current number of CVEs shipped by Microsoft this year exceeds the total number of CVEs shipped in all of 2018.” Wowza. While it’s fun to watch from a purely speculative standpoint, as in: "Will Microsoft top 300 next month?", our thoughts and prayers are nonetheless with sysadmins and vulnerability management teams drowning in the AI-induced vulnpocalypse by now. None of the Patch Tuesday security holes are listed as under attack – at least not yet – but three are listed as publicly known. Let’s take a look at those first. Three known vulnerabilities CVE-2026-49160 is an HTTP.sys denial of service vulnerability that we wrote about earlier this month. Calif researcher Quang Luong discovered the attack with an assist from OpenAI's Codex agent, named it HTTP/2 Bomb, and said it exploits the HTTP/2 header compression algorithm by sending thousands of tiny messages to the server, forcing it to rapidly allocate memory and ultimately crash. At the time, a Microsoft spokesperson told The Register that Redmond was “aware and actively investigating appropriate mitigations.” On Tuesday, the tech giant fixed the security issue by introducing a new MaxHeadersCount registry setting, which allows users to limit the number of headers included in HTTP/2 and HTTP/3 requests, and should prevent denial-of-service attacks. CVE-2026-50507, a security feature bypass bug in Windows BitLocker, is the second CVE listed as publicly disclosed, and “exploitation more likely.” An attacker with physical access to the vulnerable system could bypass the BitLocker Device Encryption feature and gain access to the device's encrypted data, according to the advisory. This flaw also seems to be a patch for one of the zero-days dropped in the ongoing war between Microsoft and a disgruntled bug hunter known as Nightmare Eclipse - likely the YellowKey vulnerability disclosed in May. Nightmare has published details about and in some cases, full proof-of-concept exploit code for six zero-days, and promised a “bone shattering” release on June 14. The third publicly known bug, CVE-2026-45586, is a Windows Collaborative Translation Framework (CTFMON) elevation of privilege vulnerability that can be abused by an authorized attacker to elevate privileges locally and gain SYSTEM access. From there, miscreants could deploy malware, steal data, and move laterally through the victim's environment - so patch this one sooner. Plus these two (of 38) critical bugs In addition to those three known vulnerabilities that made the rounds before Microsoft issued a patch, a couple of critical-rated 9.8 security flaws are worth highlighting this month. The first, CVE-2026-45657, is a Windows kernel remote code execution (RCE) bug that allows remote, unauthenticated attackers to run code with system-level privileges without any user interaction. It’s due to an error in how the Windows kernel processes some TCP/IP data, and can be exploited by sending malicious network packets to a vulnerable Windows system, thus triggering the flaw. While it’s listed as “exploitation less likely” by Redmond, we like Childs’ response. “Rest assured that every researcher and bug shop on the planet is reversing this patch right now trying to create an exploit,” he said. “Test and deploy this patch quickly.” CVE-2026-47291, an HTTP.sys RCE vulnerability that also earned a 9.8 CVSS rating, deserves attention as it can also be triggered with zero user interaction and Microsoft says it’s “more likely” to be exploited. “This vulnerability creates severe business risk because HTTP.sys is used by Windows services that process HTTP traffic,” Alex Vovk, CEO and co-founder of patch-management vendor Action1, told The Register. “A successful attack could lead to server takeover, malware deployment, data theft, service disruption, and lateral movement across the environment. Internet-facing systems are especially exposed.” The good news: systems using the Windows HTTP stack’s default MaxRequestBytes registry value are not affected. In the advisory, Redmond provides detailed instructions on how to edit registry settings, which can buy admins some time (and security) while deploying the patch. ®