How severe is CVE-2025-49666?

CVE-2025-49666 has a CVSS 3.x base score of 7.2, rated high severity. It is exploitable over network with low attack complexity, requires high privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2025-49666 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (63rd percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2025-49666?

CVE-2025-49666 primarily affects Microsoft Windows Server 2016. In total, 5 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2025-49666?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

Does CVE-2025-49666 have an EU (EUVD) identifier?

Yes. CVE-2025-49666 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2025-20578.

When was CVE-2025-49666 published?

CVE-2025-49666 was published on 2025-07-08 and last updated on 2026-06-17.

CVE-2025-49666

CVE-2025-49666 is a high-severity vulnerability in Microsoft Windows Server 2016 with a CVSS 3.x base score of 7.2. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-122.

Key facts

Severity: High (CVSS 3.x base score 7.2)
EPSS exploit prediction: 1% (63rd percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2025-20578
Weakness: CWE-122
Affected product: Microsoft Windows Server 2016
Published: 2025-07-08
Last modified: 2026-06-17

Description

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

Frequently asked questions

What is CVE-2025-49666?: Heap-based buffer overflow in Windows Kernel allows an authorized attacker to execute code over a network.
How severe is CVE-2025-49666?: CVE-2025-49666 has a CVSS 3.x base score of 7.2, rated high severity. It is exploitable over network with low attack complexity, requires high privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2025-49666 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (63rd percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2025-49666?: CVE-2025-49666 primarily affects Microsoft Windows Server 2016. In total, 5 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2025-49666?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
Does CVE-2025-49666 have an EU (EUVD) identifier?: Yes. CVE-2025-49666 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2025-20578.
When was CVE-2025-49666 published?: CVE-2025-49666 was published on 2025-07-08 and last updated on 2026-06-17.

References

https://msrc.microsoft.com/update-guide/vulnerability/CVE-2025-49666

Affected products (5)

cpe:2.3:o:microsoft:windows_server_2016:*:*:*:*:*:*:*:*
cpe:2.3:o:microsoft:windows_server_2019:*:*:*:*:*:*:*:*
cpe:2.3:o:microsoft:windows_server_2022:*:*:*:*:*:*:*:*
cpe:2.3:o:microsoft:windows_server_2022_23h2:*:*:*:*:*:*:*:*
cpe:2.3:o:microsoft:windows_server_2025:*:*:*:*:*:*:*:*

More vulnerabilities in Microsoft Windows Server 2016

CVE-2020-1467 — Critical (CVSS 10.0): An elevation of privilege vulnerability exists when Windows improperly handles hard links. An attacker who successfully…
CVE-2020-1350 — Critical (CVSS 10.0): A remote code execution vulnerability exists in Windows Domain Name System servers when they fail to properly handle…
CVE-2021-26424 — Critical (CVSS 9.9): Windows TCP/IP Remote Code Execution Vulnerability
CVE-2021-34458 — Critical (CVSS 9.9): Windows Kernel Remote Code Execution Vulnerability
CVE-2021-28476 — Critical (CVSS 9.9): Windows Hyper-V Remote Code Execution Vulnerability
CVE-2021-26867 — Critical (CVSS 9.9): Windows Hyper-V Remote Code Execution Vulnerability

All CVEs affecting Microsoft Windows Server 2016 →

Other CWE-122 (Heap-based Buffer Overflow) vulnerabilities

CVE-2026-46752 — Critical (CVSS 10.0): Redis Lua HEAP overflow in cjson library vulnerability in Apache Kvrocks. This issue affects Apache Kvrocks: from…
CVE-2026-24822 — Critical (CVSS 10.0): Out-of-bounds Write, Heap-based Buffer Overflow vulnerability in ttttupup wxhelper (src modules). This vulnerability is…
CVE-2025-23123 — Critical (CVSS 10.0): A malicious actor with access to the management network could execute a remote code execution (RCE) by exploiting a…
CVE-2022-34819 — Critical (CVSS 10.0): A vulnerability has been identified in SIMATIC CP 1242-7 V2 (All versions < V3.3.46), SIMATIC CP 1243-1 (All versions <…
CVE-2026-44050 — Critical (CVSS 9.9): A heap-based buffer overflow in the CNID daemon comm_rcv() function in Netatalk 2.0.0 through 4.4.2 allows a remote…
CVE-2026-49841 — Critical (CVSS 9.8): FreeSWITCH is a Software Defined Telecom Stack enabling the digital transformation from proprietary telecom switches to…

Browse all CWE-122 (Heap-based Buffer Overflow) vulnerabilities →