ZeroHour

CVE-2026-69829

mass

Unauthenticated Heap Buffer Overflow RCE in Microsoft Windows Shell

CVSS 3.1
9.8 critical
EPSS
1%p62
Published
()
Modified
AI analysis

CVE-2026-69829 is a heap-based buffer overflow (CWE-122) in the Microsoft Windows Shell. According to its CVSS 3.1 vector (AV:N/AC:L/PR:N/UI:N), an unauthorized remote attacker could trigger the flaw over a network without needing privileges, user interaction, or special conditions. Successful exploitation would allow the attacker to execute code on the affected host, with high impact on confidentiality, integrity, and availability. All Windows installations that include the Windows Shell component are potentially affected, though the available data does not enumerate specific vulnerable version ranges. There is currently no known public proof-of-concept, the CVE is not in CISA's KEV, and EPSS assigns roughly a 1.1% probability of exploitation within 30 days; the related headlines note Microsoft's record patch release of 974 flaws included two other exploited Windows zero-days, but no confirmed in-the-wild exploitation of this specific CVE is documented.

What to do: Apply Microsoft's latest Windows security updates across all Windows systems, prioritizing internet-facing machines, and confirm the update covering CVE-2026-69829 is installed on each host. If patching must be deferred, reduce exposure by limiting network access to Windows services that invoke shell functionality, and monitor Microsoft's advisory, CISA KEV, and public PoC releases for signs of rising exploitation risk.

Affected
Microsoft Windows Shell (Windows operating system component)
Estimated exposure
masson the order of 1+ billion Windows devices (Windows Shell ships with every Windows installation) — The Windows Shell is present in essentially all Windows installations and Microsoft Windows' global installed base exceeds one billion devices, so the theoretical upper bound of exposure is mass, though the share of systems whose…

Order-of-magnitude estimate by the model from install counts, market share and public scan data it knows; verify before quoting.

Description

Heap-based buffer overflow in Windows Shell allows an unauthorized attacker to execute code over a network.

Weakness
CWE-122
Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

In the news

Microsoft Patches Record 974 Flaws, Including Two Exploited Windows Zero-Days

Microsoft's September Patch Tuesday fixed a record 974 flaws, including two Windows privilege-escalation zero-days actively exploited and added to CISA's KEV catalog.

Microsoft's September 2026 Patch Tuesday addressed a record 974 vulnerabilities (999 including 25 non-Microsoft CVEs), with over 110 rated critical; 723 affect Windows and 111 affect Office. Two Windows privilege-escalation zero-days are actively exploited: CVE-2026-85880, an ALPC heap-based buffer overflow, and CVE-2026-81963, an improper link resolution flaw in the Windows Update Stack, both allowing attackers to gain SYSTEM privileges. CISA added both flaws to its KEV catalog, giving federal civilian agencies until September 22, 2026 to apply fixes. Volexity, Proofpoint, MSTIC, and independent researchers were credited with the reports; notable additional fixes include network-reachable RCEs in Exchange, SharePoint, SQL Server, Remote Desktop Services, DNS, and DHCP.

The Hacker News · 6d agoExploit / PoC in the wildCVE-2026-85880CVE-2026-81963CVE-2026-55007+9 CVEs

Microsoft Plugs Nearly 1,000 Security Holes

Microsoft's September Patch Tuesday fixes a record 974 flaws, including two actively exploited Windows zero-days and critical DNS and Windows Shell bugs.

Microsoft released fixes for 974 vulnerabilities, its largest-ever monthly patch batch, bringing the 2026 total above 2,600. Two zero-day privilege elevation flaws, CVE-2026-81963 and CVE-2026-85880, are being actively exploited. Critical bugs include CVE-2026-69730, an unauthenticated DNS weakness in Windows Server 2012 onward and Windows 10 deemed likely to be exploited, and CVE-2026-69829, a CVSS 9.8 Windows Shell remote code execution flaw requiring no privileges or user interaction. Microsoft and other vendors credit AI-assisted discovery for the growing patch volumes.