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Windows Remote Desktop Client Vulnerability Allows Attackers to Execute Remote Code

Microsoft patched CVE-2026-69485, an 8.8 CVSS RCE flaw in the Windows Remote Desktop Client affecting Windows 10/11 and Server 2016-2025.

Microsoft's September 2026 updates fix CVE-2026-69485, an Important-rated remote code execution vulnerability (CVSS 3.1: 8.8, temporal 7.7) in the Windows Remote Desktop Client caused by use of an uninitialized resource. An authenticated attacker with low privileges could send a specially crafted network request to execute code on an affected server, with no user interaction required. Microsoft says the flaw was not publicly disclosed before patching and rates exploitation as 'Less Likely' with no evidence of active exploitation. Affected products span Windows Server 2016, 2019, 2022 and 2025 and Windows 10 (1607-22H2) and Windows 11 (23H2-26H1), with fixes delivered via KBs including KB5123099, KB5122876 and KB5122882.

Microsoft security advisory – September 2026 monthly rollup (AV26-896) – Update 1

Canada's Cyber Centre relays Microsoft's September 2026 rollup; CISA added exploited zero-days CVE-2026-85880 and CVE-2026-81963 to KEV.

Advisory AV26-896 from the Canadian Centre for Cyber Security summarizes Microsoft's September 2026 monthly security rollup, listing affected products across Windows, Office, .NET, Azure, Exchange and SQL Server. It notes Microsoft confirmed CVE-2026-81963 and CVE-2026-85880 have been exploited. On September 8, 2026, CISA added both CVEs to its Known Exploited Vulnerabilities catalog, and administrators are urged to apply the updates.

Four groups caught using the same Chrome and Windows exploit kit

Proofpoint reports at least four hacking groups, some China-linked, share the BlueMoon exploit kit chaining Chromium and Windows kernel vulnerabilities to install malware.

Proofpoint named the nearly identical kit BlueMoon; it chains two Chromium vulnerabilities with one Windows kernel privilege-escalation flaw affecting Windows 10 (October 2018 Update and 2004), Windows Server 2019 and 2022, and the initial Windows 11 release. All three vulnerabilities received patches within 24 hours of the activity. The kit is being actively used by at least four hacking groups, some with Chinese government ties. Proofpoint links the rapid, visible sharing of a historically rare full browser exploit chain to the Chromium supply-chain patch gap and AI-assisted exploit development.

Proofpoint Threat Insightupdated · 6d agofirst · 6d agoExploit / PoC in the wild 3 sources1

Four Nation-State Actors Used the Same Chrome Zero-Day Exploit Kit Within 12 Days

Proofpoint reports four nation-state actors, mostly China-nexus, adopted the BlueMoon Chrome and Windows zero-day exploit kit within 12 days, targeting US organizations.

Proofpoint tracked an exploit kit dubbed BlueMoon that chains CVE-2026-85046, a Chrome V8 type-confusion bug, with an unnamed V8 sandbox escape and CVE-2026-85880, a Windows kernel privilege escalation using ALPC and the Windows Notification Facility. The first observed use was by China-nexus TA412 (APT31, Violet Typhoon, JungleBamboo) on August 28, 2026 against US NGOs, mining companies, and commodity trading firms, followed by UNK_LateNight targeting US aerospace and defense companies on September 2. Both V8 bugs were patch-gap zero-days: the fix was committed to Chromium on August 7 but reached stable Chrome on September 3, enabling rapid weaponization from public patches. TA412's post-exploitation payload, GemStone, is a malicious browser extension posing as an AI-powered Google Gemini companion that captures keystrokes, cookies, screenshots, and browsing history via a Cloudflare Worker C2.

Security Affairsupdated · 4h agofirst · 6d agoExploit / PoC in the wild 17 sourcesCVE-2026-85046CVE-2026-858801

September 2026 Patch Tuesday: Record patch count, 2 zero-days, and a SigRed successor

Microsoft's September 2026 Patch Tuesday delivers a record patch count, fixing two exploited zero-days and a wormable DNS flaw dubbed a SigRed successor.

Microsoft's September 2026 Patch Tuesday sets another record patch count, fixing two vulnerabilities exploited as zero-days: CVE-2026-81963, a Windows Update Stack low-privilege-to-SYSTEM escalation reported by MSTIC, and CVE-2026-85880, a Windows Advanced Local Procedure Call escalation reported by Proofpoint. Zero Day Initiative's Dustin Childs urges priority on a cluster of 20 potentially wormable bugs including DNS RCE CVE-2026-69730, described as a spiritual successor to SigRed, plus Kerberos authentication bypass CVE-2026-69676 that could give any authenticated domain user RCE on domain controllers, and Exchange RCE CVE-2026-55007 via a malicious Visio attachment. All Windows fixes are bundled in cumulative updates, and experts stress prioritizing exploitable, reachable flaws over raw patch counts.

Help Net Security · 7d agoAdvisory in the wildCVE-2026-81963CVE-2026-85880CVE-2026-69730+4 CVEs

September 2026 Microsoft Patch Tuesday, (Tue, Sep 8th)

Microsoft's September 2026 Patch Tuesday fixes a record 973 vulnerabilities, including 113 critical and two Windows privilege-escalation flaws already exploited in the wild.

Microsoft patched 973 vulnerabilities this month, its largest Patch Tuesday ever and far above the previous record of 664 set in July 2026, with 113 rated critical. Two Important elevation-of-privilege flaws (CVSS 7.8) are confirmed exploited in the wild: CVE-2026-81963 in the Windows Update Stack (improper link resolution, affects Windows 11 and Server 2025) and CVE-2026-85880 in Windows ALPC (heap-based buffer overflow allowing sandbox escape to SYSTEM, affects Windows 10 and Server 2012-2022). Critical unauthenticated RCEs (CVSS 9.8) were also fixed in Skype for Business Server (CVE-2026-66302), Windows Message Queuing (CVE-2026-69579), and Windows RRAS (CVE-2026-69590). SANS urges prioritizing the two exploited EoP fixes, then patching exposed MSMQ, RRAS, and Skype for Business deployments.

CVE-2026-50522: Microsoft SharePoint Server RCE Vulnerability

CVE-2026-50522 is an unauthenticated .NET deserialization RCE in SharePoint Server Subscription, 2019, and 2016; Microsoft patched it July 14, 2026.

CVE-2026-50522 (CWE-502) lets unauthenticated attackers send crafted serialized .NET payloads to network-accessible SharePoint endpoints, triggering gadget-chain deserialization and remote code execution under the privileged SharePoint service account. It affects SharePoint Server Subscription Edition, SharePoint Server 2019, and SharePoint Server 2016 Enterprise; Microsoft published the advisory on July 14, 2026. The EPSS score is 20.346%, but no public PoC exists and the flaw is not in CISA's KEV catalog at publication. Mitigations include applying Microsoft updates, rotating SharePoint machine keys, enabling AMSI, and restricting internet exposure.

Researchers Disclose AI-Assisted SharePoint Exploit Chain Reaching Unauthenticated RCE

Rapid7 disclosed CVE-2026-55040, a SharePoint JWT validation bypass chaining into CVE-2026-63520 unauthenticated RCE, with research substantially AI-agent-assisted; patches released.

Rapid7 disclosed CVE-2026-55040 (CVSS 9.1), several JWT validation pipeline issues letting unauthenticated attackers impersonate chosen SharePoint users by SID or UPN, chained with CVE-2026-63520 (CVSS 8.1), an unsafe .NET type instantiation in Business Connectivity Services yielding RCE as the service account. An AI agent contributed significantly across 96 sessions and roughly 80,000 tool calls over 24 active days, though an expert had to steer it and it repeatedly overstepped its threat model. No exploitation of the bypass had been reported as of CISA's July 14 assessment. The RCE affects SharePoint Subscription Edition, 2019, and 2016, plus Project Server 2013 SP1 and Office Web Apps 2013 SP1; the July updates break the chain.