EUVD-2026-29583
GHSA-4rqj-478v-ccjv
Severity by source
AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Local authenticated user (AV:L/PR:L) triggers a low-complexity kernel heap overflow yielding SYSTEM, so full C:H/I:H/A:H with unchanged scope.
Primary rating from NVD.
CVSS VectorNVD
Lifecycle Timeline
2DescriptionCVE.org
Heap-based buffer overflow in Windows TCP/IP allows an authorized attacker to elevate privileges locally.
Articles & Coverage 1
AnalysisAI
Local privilege escalation in the Microsoft Windows TCP/IP stack (tcpip.sys) lets an already-authenticated low-privileged user corrupt heap memory to gain SYSTEM-level control across virtually all supported Windows client and server releases. Microsoft assigns CVSS 7.8 and reports total technical impact, but SSVC exploitation status is 'none' and EPSS is only 0.06% (18th percentile), and there is no public exploit identified at time of analysis. Microsoft has released a patch via the Security Update Guide.
Technical ContextAI
The flaw sits in the Windows TCP/IP networking stack (implemented primarily in the kernel-mode driver tcpip.sys), a core OS component that processes IP/TCP/UDP packet structures. CWE-122 (heap-based buffer overflow) indicates that attacker-influenced data is written past the bounds of a heap-allocated buffer, corrupting adjacent kernel heap structures. Because the vulnerable code runs in kernel context, controlled corruption of pool memory can be leveraged to overwrite function pointers or object metadata and redirect execution or elevate the caller's token. The CPE set spans microsoft:windows_10 (1607, 1809, 21H2, 22H2), microsoft:windows_11 (22H3, 23H2, 24H2, 25H2, 26H1) and Windows Server (2012 through 2025), confirming this is an OS-kernel-level defect rather than an application bug.
RemediationAI
Apply the Microsoft security update for CVE-2026-33837 - a vendor-released patch is available via the Security Update Guide at https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-33837 - and install the fixed build for your specific SKU (for example 10.0.26100.8457 for Windows 11 24H2, 10.0.22631.7079 for 23H2/22H3, 10.0.19045.7291 for Windows 10 22H2, 10.0.20348.5139 for Server 2022, and 10.0.26100.32860 for Server 2025); these arrive through standard monthly Windows Update/WSUS channels. No documented product-specific workaround exists for a kernel TCP/IP heap overflow, so if patching must be delayed, rely on compensating controls: because exploitation requires an authenticated local foothold, restrict interactive and remote-shell logon rights, enforce least privilege to limit which accounts can run untrusted code, and apply application allowlisting/EDR to detect the local execution needed to trigger the flaw - with the trade-off that these reduce but do not eliminate exposure and add administrative overhead. Cross-reference the advisory at https://vuldb.com/vuln/363132 and https://nvd.nist.gov/vuln/detail/CVE-2026-33837 for build tracking.
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Same weakness CWE-122 – Heap-based Buffer Overflow
View allSame technique Buffer Overflow
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External POC / Exploit Code
Leaving vuln.today