A CVSS 9.8 authentication bypass in nginx-ui, the popular open-source web management interface for Nginx servers, is being actively exploited in the wild. The flaw, codenamed MCPwn by Pluto Security, exists because the /mcp_message endpoint added for Model Context Protocol (AI integration) support only checks IP whitelisting - and the default whitelist is empty, meaning it allows all connections. One unauthenticated HTTP POST request lets an attacker invoke all MCP tools: rewrite Nginx config files, reload the server, intercept all traffic, and harvest admin credentials. Attackers chain it with CVE-2026-27944 (exposed encryption keys via the backup API) to extract the node_secret needed for full MCP access. Recorded Future flagged active exploitation and assigned a risk score of 94/100. Shodan shows 2,600 publicly exposed instances, mostly in China, the US, Indonesia, and Germany. Pluto Security's key lesson: AI integration endpoints expose the same capabilities as the core application but often skip its security controls.
Just days after Microsoft patched BlueHammer (CVE-2026-33825) in Tuesday's Patch Tuesday, the same researcher 'Chaotic Eclipse' (aka Nightmare-Eclipse) has released a second Microsoft Defender local privilege escalation zero-day called RedSun. The exploit works on fully-patched Windows 10, Windows 11, and Windows Server systems with Windows Defender enabled, even after installing this week's April updates. The flaw abuses Defender's cloud file rollback behavior: when Defender detects a file with a 'cloud tag' it tries to restore it to its original location without validating the target path. The exploit uses NTFS junctions and opportunistic locks to redirect the write to C:\Windows\System32, overwriting system files like TieringEngineService.exe to gain SYSTEM privileges. Huntress Labs is reporting all three recently-leaked Windows Defender zero-days (BlueHammer, RedSun, and UnDefend) are now being exploited in the wild. The researcher has threatened to drop more severe RCE exploits in protest of how Microsoft handled their disclosure process. No patch available for RedSun yet. Working PoC code is public on GitHub.
One of the most methodical WordPress supply chain attacks ever: a buyer known only as 'Kris' purchased the entire Essential Plugin portfolio (30+ free WordPress plugins) on the Flippa marketplace for six figures. In August 2025, they injected a PHP deserialization backdoor in version 2.6.7, disguised as a compatibility check for WordPress 6.8.2. The malicious code sat dormant for eight months, building trust. On April 5-6, 2026, the attacker activated it - the C2 domain analytics.essentialplugin[.]com began distributing payloads to every site running the compromised plugins. The backdoor injected cloaked SEO spam into wp-config.php, visible only to Googlebot. WordPress.org permanently closed all 31 plugins on April 7 and pushed a forced auto-update - but the cleanup only removed the phone-home code, not the wp-config.php modifications, meaning compromised sites still served spam after the 'fix'. This happened the same week as the Smart Slider 3 supply chain attack we reported April 11 - two different supply chain attacks via the WordPress trusted update channel in one week.
Cisco has patched four critical vulnerabilities this week across Webex and Identity Services Engine (ISE). The standout flaw is CVE-2026-20184 in Cisco Webex Services with SSO integration via Control Hub - it allows an unauthenticated remote attacker to impersonate any user in the service due to incorrect certificate validation in the SSO flow. This is particularly dangerous for organizations using Webex with SAML and centralized identity management. Alongside it: CVE-2026-20180 and CVE-2026-20186 (both CVSS 9.9) affect Cisco ISE and ISE Passive Identity Connector, allowing authenticated attackers with even read-only admin credentials to execute arbitrary commands on the underlying OS and escalate to root. CVE-2026-20147 is a path traversal flaw in the same products. ISE versions before 3.2, plus 3.2, 3.3, 3.4, and 3.5 branches are all affected. No workarounds - only software updates fix these. In single-node ISE deployments, exploitation can also knock the node offline, blocking network access for unauthenticated endpoints.
Booking.com has confirmed unauthorized access to its systems that exposed guest reservation data including names, email addresses, phone numbers, postal addresses, booking details, and any messages shared with accommodation providers. The company began emailing affected customers over the weekend but did not send alerts via the Booking.com app, creating confusion about whether the notification emails were legitimate. Booking.com says financial data was not accessed. The company has reset PIN numbers for affected reservations. The number of impacted users has not been disclosed, though Booking.com lists 6.8 billion bookings since 2010 across 30+ million properties. Reddit users are already reporting scam messages from people who appear to have real reservation details, suggesting attackers are using the stolen data for targeted phishing. The Register notes this follows a similar 2021 breach pattern where attackers compromised hotel staff logins to access the platform.
The FBI Atlanta Field Office and Indonesian authorities have dismantled the W3LL global phishing platform and arrested its alleged developer. W3LL sold a sophisticated phishing kit designed specifically for bypassing multi-factor authentication on Microsoft 365 accounts using adversary-in-the-middle (AiTM) techniques. The platform operated as a phishing-as-a-service ecosystem with its own marketplace, support channels, and licensing model, enabling thousands of business email compromise campaigns targeting corporate Microsoft 365 environments. This is described as the first coordinated international law enforcement action against this platform. Group-IB previously estimated W3LL's tools had been used to compromise over 8,000 Microsoft 365 business accounts.
Adobe has released an emergency security update (APSB26-43, priority-1) to patch CVE-2026-34621, the Adobe Reader zero-day we reported on April 10 that had been exploited since December 2025 via malicious PDF documents. The flaw has now been classified as a prototype pollution vulnerability leading to arbitrary code execution - more severe than the initial fingerprinting and data theft we described. Adobe confirmed it's worse than just information leakage: the underlying bug can achieve full RCE, not just the reconnaissance stage observed in early exploitation. CVSS was initially scored 9.6 but Adobe revised it down to 8.6 after changing the attack vector from Network to Local. EXPMON researcher Haifei Li, who first disclosed the flaw, was credited by Adobe. All users on Windows and macOS should update immediately - Adobe assigned this patch its highest priority rating.
Attackers compromised Nextend's update infrastructure and pushed a fully weaponized version of Smart Slider 3 Pro (3.5.1.35) through the official WordPress and Joomla update channel on April 7. Sites with auto-updates enabled received a multi-layered remote access toolkit disguised as a legitimate plugin update. The malicious version was live for approximately six hours before detection. Patchstack's analysis found: unauthenticated remote command execution via crafted HTTP headers, a second authenticated backdoor with PHP eval and OS command execution, a hidden administrator account (prefixed wpsvc_) invisible in the admin interface, persistent backdoors planted in the active theme's functions.php and wp-config.php, and automated credential theft sent to an external server. Traditional defenses like firewalls, nonce verification, and role-based access controls are irrelevant here because the malicious code arrived through the trusted update channel. Affected sites should be considered fully compromised.
Attackers compromised a backend API on CPUID's website and replaced the official download links for CPU-Z and HWMonitor with trojanized versions containing the STX RAT. The attack lasted approximately six hours between April 9-10, timed to when the lead developer was on holiday. The malicious packages used DLL sideloading - legitimate CPUID executables (still properly signed) were bundled alongside a malicious CRYPTBASE.dll that masquerades as a standard Windows library. When users launched HWMonitor or CPU-Z, the malicious DLL loaded and deployed the RAT entirely in memory, with four independent persistence paths. The primary goal was browser credential theft, specifically targeting Chrome's IElevation COM interface to dump and decrypt saved passwords. The same threat group previously compromised FileZilla downloads in early March 2026. CPUID's signed original files were not tampered with - this was an infrastructure attack redirecting download links to attacker-controlled Cloudflare R2 storage.
An unpatched zero-day in Adobe Acrobat Reader has been actively exploited since at least November 2025 using booby-trapped PDF documents. The exploit, discovered by EXPMON researcher Haifei Li, works on the latest version of Adobe Reader without any user interaction beyond opening the file. It abuses privileged Acrobat JavaScript APIs (util.readFileIntoStream and RSS.addFeed) to silently harvest local files, OS details, language settings, and the Reader version from the victim's machine, then sends everything to an attacker-controlled server. The PDFs use Russian-language lures related to the oil and gas industry. The attack is a two-stage operation: the first pass fingerprints the target, and if the system meets the attacker's criteria, a follow-on RCE or sandbox escape payload is delivered. Only 5 out of 64 antivirus engines on VirusTotal detected the sample. No CVE has been assigned and no patch is available.
TrustStrike Labs