CISA confirms exploitation of two Windows zero-days among 973 Microsoft patches; 22,000 Exchange servers remain unpatched.
Microsoft's September Patch Tuesday sets a record with 973 vulnerabilities, and CISA confirms CVE-2026-81963 and CVE-2026-85880 are being exploited, giving federal agencies until September 22 to patch. Nightwing estimates over 22,000 corporate Exchange servers are unpatched against weaponized exploit code. Analysts describe CVE-2026-81963 as an early link in ransomware chains where phishing leads to privilege escalation, and note year-to-date Microsoft disclosures exceed 2,600 bugs.
Arctic Wolf tracks PREY-0058 (linked to UNC6671), a vishing campaign stealing Microsoft 365 session tokens via AiTM panels for SaaS data theft and extortion.
Arctic Wolf is tracking a campaign, PREY-0058, sharing tradecraft with Google Threat Intelligence Group's UNC6671, in which callers posing as internal IT talk employees through fake passkey/MFA setups. Operator-controlled adversary-in-the-middle pages harvest passwords and MFA approvals to seize session tokens, then actors enumerate and bulk-exfiltrate data from SharePoint, OneDrive, Exchange, and Box. Extortion brands include BlackFile, Pink, Helix, Cinder, and Redact; targets are mostly US-based executives in construction, healthcare, real estate, finance, and professional services, with exfiltration shifting to residential proxies like NodeMaven.
Arctic Wolf tracks PREY-0058 posing as IT help desk to steal Microsoft 365 sessions via AiTM panels, then extorting executives after SaaS data theft.
Arctic Wolf documented a threat cluster tracked as PREY-0058 that impersonates internal IT help desk staff by phone, luring Directors, VPs, and executives to authentication-themed URLs formatted as victim-organization lure domains. Adversary-in-the-middle panels intercept credentials and MFA approvals, and stolen sessions are replayed through residential proxies such as NodeMaven from IPs matching the victim's geo-location and ASN, defeating impossible-travel alerts. Attackers perform discovery against SharePoint and Entra ID, then harvest data from OneDrive, Exchange, and Box before issuing extortion demands. Defenders are advised to require managed devices, use phishing-resistant MFA like FIDO2, enable Continuous Access Evaluation, and monitor sign-ins, SharePoint SearchQueryPerformed, and MailItemsAccessed events.
Arctic Wolf tracks PREY-0058, a vishing and AitM token-theft crew targeting Microsoft 365 executives for data theft and extortion.
Arctic Wolf disclosed a widespread data theft and extortion cluster, PREY-0058, which overlaps with Mandiant's UNC6671 and possibly the Pink/Cinder extortion groups. Attackers impersonate IT help desk staff by phone, direct executives to authentication-themed lure domains, and run adversary-in-the-middle Microsoft 365 logins to harvest credentials, MFA approvals, and session tokens replayed via residential proxies such as NodeMaven. After access, they run discovery in SharePoint and Entra ID, then bulk-exfiltrate data from SharePoint, OneDrive, Exchange, and Box before sending extortion demands. Targets are primarily US construction, healthcare, real estate, finance, and professional services organizations.
xHunt deployed custom backdoors Hisoka, Killua, Gon, and EYE against Kuwait shipping and transportation organizations, using DNS tunneling and email-draft C2 channels.
Unit 42 observed the xHunt campaign targeting Kuwait transportation and shipping organizations between May and June 2019, installing backdoors named after characters from the anime Hunter x Hunter, including Hisoka, Killua, Sakabota, and Netero. The tools use HTTP and DNS tunneling for C2, and Hisoka v0.9 added an unusual email-based C2 channel that abuses Exchange Web Services with stolen credentials to exchange email drafts. The Gon tool provides port scanning, file transfer, screenshots, remote command execution, and RDP session creation, while EYE acts as a cleanup failsafe if a legitimate user logs in. Related activity targeting Kuwait between July and December 2018 was reported by IBM X-Force IRIS, suggesting the campaigns are likely related.
Microsoft's August 2026 Patch Tuesday fixes 398 CVEs, including an actively exploited WinSock zero-day CVE-2026-68820 and wormable DNS RCE CVE-2026-62878.
Microsoft's August 2026 Patch Tuesday addresses 398 CVEs across Windows, Office, Azure, Exchange Server, SharePoint, Teams, .NET and other products, with 62 rated Critical. The actively exploited CVE-2026-68820 is a use-after-free in the Windows WinSock afd.sys driver that can yield SYSTEM privileges via a race condition. CVE-2026-62878 is a critical, wormable stack buffer overflow in Windows DNS Server allowing unauthenticated, remote code execution without user interaction. Other notable fixes include WDS TFTP RCE CVE-2026-62893, a QUIC flaw affecting roughly 13.5 million sites (CVE-2026-62815), an Exchange authentication bypass EoP demonstrated at Pwn2Own Berlin (CVE-2026-62911), and two TPM 2.0 reference implementation fixes.
Local Privilege Escalation via Link Following in Windows Update Stack
CVE-2026-81963 is a link-following flaw (CWE-59, improper link resolution before file access) in the Microsoft Windows Update Stack, in which the component fails to correctly resolve file links before opening them. A local attacker with low privileges can plant or manipulate a link (symlink/junction) that the privileged update stack follows during operation, redirecting its file access to an attacker-controlled target. The result is local privilege escalation — CVSS 3.1 rates this 7.8 (high) with high confidentiality, integrity, and availability impact — allowing an authorized local user or malware already on the machine to gain elevated rights. Affected products are Windows 11 23H2, 24H2, 25H2, and 26H1 and Windows Server 2025; any unpatched system on those versions is exposed to any local account holder. The flaw was fixed in Microsoft's record September 2026 Patch Tuesday (974 CVEs), was added to CISA's KEV on 2026-09-08 as one of two Windows zero-days reported as exploited in the wild, and has no known public PoC or confirmed ransomware use.
· Microsoft Windows 11 23H2, 24H2, 25H2, 26H1 · Microsoft Windows Server 2025 KEVmass
Heap-Based Buffer Overflow in Windows ALPC Enables Local Privilege Escalation
CVE-2026-85880 is a heap-based buffer overflow in Windows Advanced Local Procedure Call (ALPC), the Windows mechanism for local inter-process communication. An authorized local attacker can trigger the overflow by submitting crafted input over ALPC, corrupting heap memory in the component that handles the request. Successful exploitation allows the attacker to execute code with elevated privileges, typically gaining SYSTEM-level control of the local host, which is especially valuable as a post-exploitation or sandbox-escape step. Affected products include Windows 10 (1607, 1809, 21H2, 22H2) and Windows Server 2012, 2016, 2019, and 2022, meaning most on-premises Windows estates are in scope. The flaw was fixed in Microsoft's record 974-CVE September 2026 Patch Tuesday and was added to CISA's KEV on 2026-09-08, confirming exploitation in the wild; press reports describe Windows zero-days being chained with a Chrome zero-day in 'BlueMoon' kit attacks, though the data does not explicitly confirm this CVE is the Windows flaw in that chain.
· Microsoft Windows 10 1607, 1809, 21H2, 22H2 · Microsoft Windows Server 2012, 2016, 2019, 2022 KEVmass
Use-After-Free Local Privilege Escalation in Microsoft Windows WinSock AFD Driver
CVE-2026-68820 is a use-after-free (CWE-416) in the Windows Ancillary Function Driver for WinSock (afd.sys), the kernel component that handles Winsock socket operations. A local, authenticated attacker can trigger the memory corruption through crafted socket activity, and the high attack-complexity score (AV:L/AC:H/PR:L) indicates exploitation requires a specific, likely race-sensitive sequence of operations. Successful exploitation elevates privileges to SYSTEM, giving the attacker full control of the host, and public reporting describes deployment of a backdoor after privilege escalation. Virtually every Windows 10, Windows 11, and Windows Server (2012-2022) installation ships this driver, so the affected population is essentially the entire supported Windows installed base. The flaw is being exploited in the wild: CISA added it to the KEV on 2026-08-11, Microsoft fixed it in the August 2026 Patch Tuesday release, and reporting ties active exploitation to North Korea's Lazarus group, who paired the zero-day with fake job-offer lures.
· Microsoft Windows Ancillary Function Driver for WinSock (afd.sys) as shipped with the Windows versions listed below · Microsoft Windows 10 1607, 1809, 21H2, 22H2 KEVmass
Pre-auth use-after-free RCE in Microsoft Windows Deployment Services (WDS)
Microsoft Windows Deployment Services (WDS) contains a use-after-free memory-safety flaw (CWE-416) that an unauthenticated attacker can trigger by sending crafted network traffic to the WDS service, leading to remote code execution on the target system. The vulnerability affects Windows 10 1607 and 1809 and Windows Server 2012, 2016, 2019, 2022, and 2025 on systems where WDS is deployed, a role typically used for network-based (PXE) operating system imaging. A successful exploit grants the attacker code execution with high confidentiality, integrity, and availability impact, reflected in the critical CVSS 3.1 score of 9.8 with network vector, low complexity, and no privileges or user interaction required. No public proof-of-concept, CISA KEV listing, or confirmed in-the-wild exploitation is currently known, although EPSS estimates a 2.7% probability of exploitation within 30 days (85th percentile). The flaw was disclosed alongside Microsoft's record September 2026 Patch Tuesday, which shipped nearly 1,000 fixes including two Windows zero-days.
· microsoft Windows 10 1607 · microsoft Windows 10 1809large
Unauthenticated Deserialization RCE in Microsoft HPC Pack
CVE-2026-59124 is a deserialization of untrusted data flaw (CWE-502) in Microsoft High Performance Computing (HPC) Pack that allows an unauthorized attacker to execute code over a network. Because the vulnerable component processes untrusted serialized input, an attacker who can reach the network-facing service can send malicious serialized data and trigger arbitrary code execution without credentials or user interaction. Successful exploitation grants the attacker the ability to run code in the context of the affected service, with full confidentiality, integrity, and availability impact per the 9.8 CVSS score. Any organization running Microsoft HPC Pack on Windows — typically head nodes and management endpoints of Windows HPC clusters — is affected. As of the August 2026 Patch Tuesday release that addressed it, there is no known public proof-of-concept, no CISA KEV listing, and no confirmed exploitation in the wild, though the EPSS score of 1.7% (76th percentile) suggests a moderate near-term exploitation probability.
· Microsoft HPC Pack (High Performance Computing Pack) on Windowsniche
Use-after-free RCE in Microsoft MsQuic via crafted network packets
A use-after-free (CWE-416) in Microsoft's QUIC implementation (MsQuic) allows an unauthenticated remote attacker to execute code on an affected host. The flaw arises because creating and removing new network paths in response to incoming packets can invalidate a pointer that is subsequently used. An attacker needs only to send a specially crafted packet to a service speaking QUIC, with no authentication or user interaction required; the maximum CVSS 4.0 score of 10 (critical) reflects full system-compromise potential. Any deployment of the MsQuic library is affected, including services built on Microsoft's in-box QUIC support (e.g., HTTP/3 and SMB over QUIC) and applications consuming the public NuGet package, though exact affected version ranges are not specified in the available data. Exploitation has not been observed: there is no public proof-of-concept, the issue is not in CISA's KEV, and EPSS puts the 30-day exploitation probability at about 1 percent, but a fix ('Guard path promotion', commit e0f55b5) is already available.
· Microsoft MsQuic (Microsoft QUIC library; distributed via NuGet) · Microsoft Services and applications using MsQuic (e.g., HTTP/3, SMB over QUIC, .NET System.Net.Quic)mass
Unauthenticated Stack Buffer Overflow RCE in Windows DNS (CVE-2026-62878)
Windows DNS contains a stack-based buffer overflow (CWE-121) that an unauthenticated, network-adjacent or internet-reachable attacker can trigger by sending crafted input to the DNS service. Successful exploitation yields remote code execution on the target host, with high impact on confidentiality, integrity and availability (CVSS 3.1: 9.8). The flaw affects the DNS component shipped with Windows 10 1607 and 1809 and with Windows Server 2012, 2016, 2019, 2022 and 2025; systems running the DNS Server role, especially internet-facing DNS servers and domain controllers, are the primary targets. Microsoft, which assigned the CVE, has issued a fix, and the flaw appeared amid a record-sized run of Patch Tuesday releases. No in-the-wild exploitation is currently known: it is not in CISA's KEV, no public proof-of-concept is available, and EPSS estimates only a 1.3% probability of exploitation within 30 days.
· microsoft Windows 10 1607 · microsoft Windows 10 1809mass
Capture-Replay Authentication Bypass in Microsoft Exchange Server
Microsoft Exchange Server contains an authentication bypass flaw (CWE-294) in which captured authentication material can be replayed, allowing an authorized attacker to elevate privileges over a network. Per the CVSS vector, the attack is network-based with low complexity but requires the attacker to already hold low privileges and some user interaction, and success yields high impact on confidentiality, integrity, and availability. Affected products include on-premises Exchange Server and Exchange Server Subscription Edition, though specific vulnerable version ranges are not specified in the available data. Public scans indicate nearly 22,000 Exchange servers remain exposed to the flaw following the August 2026 Patch Tuesday fixes. No in-the-wild exploitation, public proof-of-concept, or KEV listing is known; the bug was demonstrated at Pwn2Own (ZDI-26-534) and carries an EPSS estimate of 1.3% probability of exploitation within 30 days.
· microsoft exchange server · microsoft exchange server subscription editionlarge
Local Privilege Escalation via Link Following in Windows User Profile Service
CVE-2026-62832 is a local privilege escalation flaw (CWE-59, improper link resolution, or 'link following') in the Windows User Profile Service. An attacker who already holds a limited local account on an affected machine can cause the service to follow a symbolic link or junction before it validates file access, so the service performs file operations with elevated rights. Successful exploitation grants elevated privileges on the local system — typically up to administrator/SYSTEM level — with no user interaction required. Affected platforms include Windows 10 21H2 and 22H2, Windows 11 23H2 through 26H1, and Windows Server 2022 and 2025, which together span essentially the entire supported Windows estate. As of this analysis there is no public proof-of-concept, no CISA KEV listing, and no confirmed in-the-wild exploitation of this specific flaw; EPSS estimates a 3.3% (88th percentile) chance of exploitation within 30 days, although Microsoft's August 2026 Patch Tuesday fixed 400+ vulnerabilities and a separate zero-day (CVE-2026-68820) is under active attack.
· microsoft Windows 10 21H2 · microsoft Windows 10 22H2mass
Local Tampering via Link-Following Flaw in Windows 11 26H1 Container Isolation Driver
CVE-2026-72971 is a link-following flaw (CWE-59) in the Windows Container Isolation FS Filter Driver (unionfs.sys) on Windows 11 26H1: the driver performs file access without fully verifying that the path is not redirected through a symbolic link or junction. A local attacker who already holds low-privilege access (CVSS AV:L/PR:L, no user interaction required) can plant a malicious link at a location the driver processes, causing it to follow the link and act on an attacker-chosen target. The attacker gains tampering capability, which the CVSS scores as High integrity impact with no confidentiality or availability impact, meaning they can modify or overwrite files their account could not normally change. Any Windows 11 26H1 system is in scope per the CVE data, with the highest practical risk on shared or multi-user hosts and machines using container isolation features where unionfs.sys is active. No active exploitation is known: the CVE is not in CISA KEV, no public proof-of-concept exists, and EPSS puts 30-day exploitation probability at about 0.5%; the related news shows Microsoft's August 2026 Patch Tuesday shipped 400+ fixes, and defenders should confirm their devices received the unionfs.sys patch.
· microsoft Windows 11 26H1 (Container Isolation FS Filter Driver, unionfs.sys)mass
Entities are extracted by the model from each article. Watching an entity keeps it in this browser only (no account); the watchlist page and dashboard alerts use it.