CVE-2025-47981: SPNEGO Extended Negotiation (NEGOEX) Security Mechanism Remote Code Execution Vulnerability

CVE-2025-47981 is a remote code execution vulnerability in SPNEGO Extended Negotiation (NEGOEX) Security Mechanism, rated Critical by Microsoft, with a CVSS 3.1 base score of 9.8 (Critical). An attacker can exploit it remotely over the network, without any privileges and without user interaction. Microsoft has not reported exploitation in the wild and rates exploitation as more likely. The EPSS model estimates a 41.12% probability of exploitation activity in the next 30 days, higher than 99% of all scored vulnerabilities. Microsoft released the fix on 8 July 2025 in the July 2025 Patch Tuesday, delivered through 12 security updates (KB5062557, KB5062572, KB5062554, KB5062552 and more). It affects 33 products in 2 product families (Windows, ESU).

Key facts

CVE ID: CVE-2025-47981
Severity: Critical CVSS 9.8
Microsoft severity: Critical
Impact: Remote Code Execution
Exploited in the wild: No
Publicly disclosed: No
Exploitation likelihood: More Likely
Weakness: CWE-122
EPSS: 41.12% (percentile 99%)
CISA KEV: Not listed
Released: 8 July 2025
Last updated: 8 July 2025
Patch Tuesday: July 2025 Patch Tuesday
Product families: Windows, ESU

CVSS score and vector

Microsoft scores CVE-2025-47981 at 9.8 (temporal 8.5) using CVSS 3.1. Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C

Metric	Value
Attack vector	Network
Attack complexity	Low
Privileges required	None
User interaction	None
Scope	Unchanged
Confidentiality impact	High
Integrity impact	High
Availability impact	High
Exploit code maturity	Unproven
Remediation level	Official fix
Report confidence	Confirmed

Description

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

Frequently asked questions (Microsoft)

How could an attacker exploit the vulnerability?

An attacker could exploit this vulnerability by sending a malicious message to the server, potentially leading to remote code execution.

What is SPNEGO Extended Negotiation?

The SPNEGO Extended Negotiation Security Mechanism (NEGOEX) extends Simple and Protected GSS-API Negotiation Mechanism (SPNEGO) described in [RFC4178]. Please see SPNEGO Overview for more information.

Mitigations and workarounds

The following mitigating factors might be helpful in your situation:

This vulnerability affects Windows client machines running Windows 10, version 1607 and above, due to the following GPO being enabled by default on these operating systems: "Network security: Allow PKU2U authentication requests to this computer to use online identities".

Affected products (33)

Windows

Product	Security update	Type	Fixed build	Restart
Windows 10 Version 1809 for 32-bit Systems	KB5062557	Security Update	10.0.17763.7558	Yes
Windows 10 Version 1809 for x64-based Systems	KB5062557	Security Update	10.0.17763.7558	Yes
Windows Server 2019	KB5062557	Security Update	10.0.17763.7558	Yes
Windows Server 2019 (Server Core installation)	KB5062557	Security Update	10.0.17763.7558	Yes
Windows Server 2022	KB5062572	Security Update	10.0.20348.3932	Yes
Windows Server 2022 (Server Core installation)	KB5062572	Security Update	10.0.20348.3932	Yes
Windows 10 Version 21H2 for 32-bit Systems	KB5062554	Security Update	10.0.19044.6093	Yes
Windows 10 Version 21H2 for ARM64-based Systems	KB5062554	Security Update	10.0.19044.6093	Yes
Windows 10 Version 21H2 for x64-based Systems	KB5062554	Security Update	10.0.19044.6093	Yes
Windows Server 2025 (Server Core installation)	KB5062553	Security Update	10.0.26100.4652	Yes
Windows 11 Version 23H2 for ARM64-based Systems
Windows 11 Version 23H2 for x64-based Systems
Windows Server 2022, 23H2 Edition (Server Core installation)	KB5062570	Security Update	10.0.25398.1732	Yes
Windows 11 Version 24H2 for ARM64-based Systems	KB5062553	Security Update	10.0.26100.4652	Yes
Windows 11 Version 24H2 for x64-based Systems	KB5062553	Security Update	10.0.26100.4652	Yes
Windows Server 2025	KB5062553	Security Update	10.0.26100.4652	Yes
Windows 10 for 32-bit Systems	KB5062561	Security Update	10.0.10240.21073	Yes
Windows 10 for x64-based Systems	KB5062561	Security Update	10.0.10240.21073	Yes
Windows 10 Version 1607 for 32-bit Systems	KB5062560	Security Update	10.0.14393.8246	Yes
Windows 10 Version 1607 for x64-based Systems	KB5062560	Security Update	10.0.14393.8246	Yes
Windows Server 2016	KB5062560	Security Update	10.0.14393.8246	Yes
Windows Server 2016 (Server Core installation)	KB5062560	Security Update	10.0.14393.8246	Yes

ESU

Product	Security update	Type	Fixed build	Restart
Windows 11 Version 22H2 for ARM64-based Systems	KB5062552	Security Update	10.0.22621.5624	Yes
Windows 11 Version 22H2 for x64-based Systems	KB5062552	Security Update	10.0.22621.5624	Yes
Windows 10 Version 22H2 for x64-based Systems
Windows 10 Version 22H2 for ARM64-based Systems
Windows 10 Version 22H2 for 32-bit Systems
Windows Server 2008 R2 for x64-based Systems Service Pack 1	KB5062632 KB5062619	Monthly Rollup Security Only	6.1.7601.27820 6.1.7601.27820	Yes Yes
Windows Server 2008 R2 for x64-based Systems Service Pack 1 (Server Core installation)	KB5062632 KB5062619	Monthly Rollup Security Only	6.1.7601.27820 6.1.7601.27820	Yes Yes
Windows Server 2012	KB5062592	Monthly Rollup	6.2.9200.25573	Yes
Windows Server 2012 (Server Core installation)	KB5062592	Monthly Rollup	6.2.9200.25573	Yes
Windows Server 2012 R2	KB5062597	Monthly Rollup	6.3.9600.22676	Yes
Windows Server 2012 R2 (Server Core installation)	KB5062597	Monthly Rollup	6.3.9600.22676	Yes

Security updates (12)

KB5062557 (Security Update)
KB5062572 (Security Update)
KB5062554 (Security Update)
KB5062552 (Security Update)
KB5062553 (Security Update)
KB5062570 (Security Update)
KB5062561 (Security Update)
KB5062560 (Security Update)
KB5062632 (Monthly Rollup)
KB5062619 (Security Only)
KB5062592 (Monthly Rollup)
KB5062597 (Monthly Rollup)

Exploitation and detection

Detection and weaponization

Weaponization maturity: Exploit.

Proof-of-concept repositories (1)

HKenzoKimura/CVE-2025-47981

NIST NVD data

NVD status: Analyzed
NVD CVSS: 9.8 (CRITICAL)
NVD weakness: CWE-122
Published to NVD: 8 July 2025
NVD last modified: 26 September 2025

Affected configurations (CPE)

Product	Vulnerable versions
windows 10 1507 (x64)	before 10.0.10240.21073
windows 10 1507 (x86)	before 10.0.10240.21073
windows 10 1607 (x64)	before 10.0.14393.8246
windows 10 1607 (x86)	before 10.0.14393.8246
windows 10 1809 (x64)	before 10.0.17763.7558
windows 10 1809 (x86)	before 10.0.17763.7558
windows 10 21h2	before 10.0.19044.6093
windows 10 22h2	before 10.0.19045.6093
windows 11 22h2	before 10.0.22621.5624
windows 11 23h2	before 10.0.22631.5624
windows 11 24h2	before 10.0.26100.4652
windows server 2008 r2 (x64)	all listed versions
windows server 2012	all listed versions
windows server 2012 r2	all listed versions
windows server 2016	before 10.0.14393.8246
windows server 2019	before 10.0.17763.7558
windows server 2022	before 10.0.20348.3932
windows server 2022 23h2	before 10.0.25398.1732
windows server 2025	before 10.0.26100.4652

References

https://msrc.microsoft.com/update-guide/vulnerability/CVE-2025-47981 (Vendor Advisory)
https://www.vicarius.io/vsociety/posts/cve-2025-47981-detection-script-heap-based-buffer-overflow-in-windows-spnego-extended-negotiation (Exploit, Third Party Advisory)
https://www.vicarius.io/vsociety/posts/cve-2025-47981-mitigation-script-heap-based-buffer-overflow-in-windows-spnego-extended-negotiation (Exploit, Mitigation, Third Party Advisory)

Acknowledgments

Anonymous
Yuki Chen

Revision history

Version	Date	Description
1.0	8 July 2025	Information published.