// #patch-tuesday
20 articles
Enterprise Guide: Prioritising the June 2026 Patch Tuesday Across 198 CVEs
Security teams face 198 CVEs from Microsoft's June 2026 Patch Tuesday plus concurrent advisories from SAP, Ivanti, Palo Alto, and CISA. This guide provides a decision framework for prioritising remediation across different infrastructure tiers — from internet-facing servers to workstations — with specific guidance for each of the highest-risk vulnerabilities.
Three CVSS 9.8 Windows Flaws Demand Emergency Action: Kernel RCE, Wormable HTTP.sys, and DHCP Client
CVE-2026-45657 (Windows Kernel), CVE-2026-47291 (HTTP.sys), and CVE-2026-44815 (DHCP Client) each carry CVSS 9.8 and enable unauthenticated remote code execution. All three were publicly disclosed before Microsoft's June patch, giving attackers a head start. This article provides technical detail and remediation guidance for each flaw.
Microsoft June 2026 Patch Tuesday: 198 CVEs and Six Zero-Days Including Wormable CVSS 9.8 HTTP.sys Flaw
Microsoft's June 2026 Patch Tuesday addresses 198 vulnerabilities across Windows, Office, Azure, and server components — including three CVSS 9.8 critical remote code execution flaws and six publicly disclosed zero-days. HTTP.sys CVE-2026-47291 is wormable, requiring no authentication or user interaction against any Windows Server with IIS or HTTP API exposed.
Windows Kerberos KDC Remote Code Execution CVE-2026-47288 Puts Domain Controllers at Critical Risk
CVE-2026-47288 is a critical remote code execution vulnerability in the Windows Kerberos Key Distribution Centre that allows network-adjacent unauthenticated attackers to execute arbitrary code on Active Directory domain controllers. All supported Windows Server versions are affected. Domain controllers should be treated as the highest-priority patch target in the June 2026 update cycle.
Fortinet Patches Critical Vulnerabilities in FortiAuthenticator and FortiSandbox — Enterprise SSO and Security Infrastructure at Risk
Fortinet released patches for critical vulnerabilities in FortiAuthenticator and FortiSandbox as part of the May 2026 patch cycle. FortiAuthenticator flaws can enable authentication bypass and session manipulation in enterprise SSO deployments, while FortiSandbox issues affect the analysis platform. Apply patches immediately given Fortinet's established exploitation history.
Microsoft May 2026 Patch Tuesday Fixes 120 Vulnerabilities — No Zero-Days but Wormable RCEs Demand Immediate Action
Microsoft released 120 security fixes in May's Patch Tuesday update, including 17 Critical-rated vulnerabilities and no actively exploited zero-days. Among the most significant are a network-based Windows DNS Client RCE and an authenticated SharePoint Server RCE. Security teams should prioritise network-facing systems within 48 hours.
SharePoint Server RCE and Office Preview Pane Vulnerabilities Fixed in May Patch Tuesday — Enterprise Document Attack Surface Elevated
May's Patch Tuesday patches an authenticated RCE in SharePoint Server (CVE-2026-40365) and multiple Office vulnerabilities exploitable via the Windows Explorer and Outlook preview pane without opening files. Together they represent a significant enterprise document attack surface. Assess SharePoint exposure and validate Office update deployment this week.
Windows DNS Client RCE CVE-2026-41096: Attacker-Controlled DNS Servers Can Trigger Memory Corruption on All Windows Versions
CVE-2026-41096 in the Windows DNS Client allows an attacker controlling a DNS server to send a crafted response that triggers memory corruption on any Windows system performing standard DNS resolution. No user interaction or authentication is required, and the flaw affects all supported Windows versions. Patch network-facing systems within 24 hours.
Azure IoT Central Privilege Escalation via Sensitive Data Exposure — CVSS 9.9
A CVSS 9.9 privilege escalation vulnerability in Azure IoT Central exposes sensitive platform data allowing authenticated low-privilege attackers to gain administrative control. April 2026 Patch Tuesday addressed the flaw — audit IoT Central role assignments and rotate provisioning credentials now.
Microsoft Bing Remote Code Execution via Deserialization — CVSS 10.0 Patch Now
A critical CVSS 10.0 unauthenticated RCE vulnerability in Microsoft Bing allows attackers to execute arbitrary code over the network via unsafe deserialization. Patched in April 2026 Patch Tuesday — update immediately.
Wormable Windows TCP/IP Race Condition RCE (CVE-2026-33827) — IPv6-Enabled Networks Face EternalBlue-Class Propagation Risk
A race condition in the Windows TCP/IP stack allows unauthenticated remote code execution against systems with IPv6 or IPSec enabled, demonstrated at Pwn2Own 2026 and patched in April's Patch Tuesday. The vulnerability's wormable characteristics — no user interaction, no authentication, network-adjacent propagation — place it in the same risk category as EternalBlue for environments that have not applied the April update.
April Patch Tuesday Bug Crashes LSASS on PAM-Enabled Domain Controllers — No Fix Yet
KB5082063, Microsoft's April 2026 cumulative update, is causing LSASS to crash on non-Global Catalog domain controllers in Privileged Access Management environments, triggering unrecoverable reboot loops that take down Active Directory authentication. Microsoft has confirmed the issue across all Windows Server versions from 2016 to 2025 and is developing a corrected update, but none is available yet.
CVE-2026-33826: Windows Active Directory RCE via Crafted RPC Calls — Patch Now
A critical remote code execution flaw in Windows Active Directory allows any authenticated domain user to execute arbitrary code on domain controllers and other AD-joined servers by sending specially crafted RPC calls. Rated CVSS 8.0 and assessed by Microsoft as 'Exploitation More Likely', CVE-2026-33826 poses a serious lateral-movement and domain-compromise risk for every Windows Server environment. The April 2026 Patch Tuesday update provides the only full remediation.
CVE-2026-33824: Critical Windows IKE Service RCE Demands Urgent Patching
A CVSS 9.8 double-free vulnerability in the Windows Internet Key Exchange service allows unauthenticated remote attackers to achieve SYSTEM-level code execution on all supported Windows versions. With no user interaction required and confirmation of pre-patch exploitation, every unpatched Windows host with IKEv2 enabled is at immediate risk. Apply the April 2026 Patch Tuesday update or block UDP ports 500 and 4500 immediately.
Microsoft Closes APT29's Favourite Phishing Door With New RDP File Protections
The April 2026 Windows update introduces mandatory security warnings and redirections-blocked-by-default for RDP connection files, directly countering the technique used by APT29 and other threat actors to silently redirect local drives and harvest credentials. Organisations using Windows 10 and 11 should confirm the KB is deployed.
Microsoft April 2026 Patch Tuesday: 167 Flaws Patched Including Two Zero-Days
Microsoft's April 2026 Patch Tuesday addresses 167 vulnerabilities, including an actively exploited SharePoint spoofing zero-day (CVE-2026-32201) and a publicly disclosed Defender elevation-of-privilege flaw. Eight Critical-rated vulnerabilities include a CVSS 9.8 IKE RCE and a Critical Active Directory RCE assessed as exploitation more likely.
CISA Flags SharePoint Zero-Day CVE-2026-32201 as Actively Exploited — Patch Arrives Tomorrow
CISA has added CVE-2026-32201, a Microsoft SharePoint Server spoofing vulnerability under active exploitation, to the KEV catalogue with a 28 April remediation deadline. The timing is unusual: Microsoft has not yet released a patch as of this alert, with the fix expected in tomorrow's Patch Tuesday release. Organisations must decide whether to implement mitigations today or accept overnight exposure until the patch lands.
Windows Kerberos Security Feature Bypass CVE-2026-24297 — Race Condition Enables Unauthenticated Network Attack
CVE-2026-24297 is a security feature bypass in the Windows Kerberos implementation caused by a race condition that can be triggered remotely without credentials or user interaction. Patched in the March 2026 Patch Tuesday, the vulnerability allows an attacker with network access to a Kerberos-speaking service to bypass security validation in the authentication flow. No active exploitation has been confirmed but the attack vector requires no credentials, increasing urgency.
March 2026 Brought 83 Patch Tuesday CVEs and Three CISA KEV Additions — How to Prioritise
March 2026's Patch Tuesday addressed 83 vulnerabilities including three critical Office RCEs, an Active Directory privilege escalation now in CISA's KEV catalogue, and a Kerberos security feature bypass. Add three separate CISA KEV additions throughout the month — F5 BIG-IP, Citrix NetScaler, and Active Directory — and security teams are managing a substantial patching backlog entering April. This analysis cuts through the volume to identify where to focus.
Active Directory Privilege Escalation CVE-2026-25177 Added to CISA KEV — Domain Admin Risk via SPN Abuse
CVE-2026-25177, a privilege escalation vulnerability in Active Directory Domain Services patched in March's Patch Tuesday, has been added to CISA's Known Exploited Vulnerabilities catalogue. An authenticated attacker with low-privileged domain credentials can exploit improper SPN and UPN name validation to escalate to domain administrator level. The KEV addition confirms in-the-wild exploitation approximately three weeks after patching was available.
Commentary tagged #patch-tuesday
The Week That Had Everything: June 2026 and What It Reveals About Enterprise Security Capacity
The week of 9–13 June 2026 delivered a record Microsoft Patch Tuesday, a CVSS 10.0 Ivanti exploit, a wormable Linux kernel proof-of-concept, Veeam and SAP critical advisories, and an accelerating ransomware worm across 66 countries. It was not a crisis — it was a normal week in 2026. That is the diagnosis.
CipherWatch Editorial
Security Intelligence Platform
When Microsoft, SAP, Ivanti, and Palo Alto All Patch Critical Flaws on the Same Day, We Have a Coordination Problem
The week of 9 June 2026 delivered critical security patches from at least four major vendors on the same day, plus a Linux kernel PoC, plus a CISA KEV batch. The security community has created a coordination structure — Patch Tuesday — that has the opposite of its intended effect: it concentrates defender workload in a single week every month while giving attackers 30 predictable days to prepare.
CipherWatch Editorial
Security Intelligence Platform
198 CVEs in One Day. Something Has Gone Wrong With How We Do Patch Management.
Microsoft's June 2026 Patch Tuesday drops 198 vulnerabilities in a single Tuesday, including six zero-days and three CVSS 9.8 remote code execution flaws. Meanwhile SAP patches 21 flaws on the same day, Cisco issues a critical advisory, and a Linux kernel PoC goes public. The security community has normalised a monthly event so large that no enterprise team can actually process it — and that normalisation is itself the problem.
CipherWatch Editorial
Security Intelligence Platform
The 'No Zero-Days' Headline Is Teaching Defenders the Wrong Lesson About Patch Tuesday
Every month that Microsoft's Patch Tuesday contains no actively exploited zero-days, security coverage softens and patching urgency drops. This framing optimises for the wrong signal — it measures whether attackers have already acted, not whether they are about to. May's Patch Tuesday has 120 vulnerabilities including a wormable DNS RCE, but the dominant headline will be the absence of zero-days.
CipherWatch Editorial
Security Intelligence Platform