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CVE-2025-59287: Microsoft Windows Server Update Service (WSUS) Deserialization of Untrusted Data Vulnerability

• Severity: critical (CVSS 9.8 v3.1)
• Exploited in the wild: yes — in CISA KEV since 2025-10-24
• EPSS: 100.0% probability of exploitation in the next 30 days
• Public exploit or detection template: yes
• Published: 2025-10-14 · updated 2026-06-17
• Weakness: CWE-502

Description

Deserialization of untrusted data in Windows Server Update Service allows an unauthorized attacker to execute code over a network.

Affected products

• Microsoft Windows Server 2012: r2
• Microsoft Windows Server 2016: before 10.0.14393.8524 — fixed in 10.0.14393.8524
• Microsoft Windows Server 2019: before 10.0.17763.7922 — fixed in 10.0.17763.7922
• Microsoft Windows Server 2022: before 10.0.20348.4297 — fixed in 10.0.20348.4297
• Microsoft Windows Server 2022, 23H2 Edition (Server Core installation): before 10.0.25398.1916 — fixed in 10.0.25398.1916
• Microsoft Windows Server 2025: before 10.0.26100.6905 — fixed in 10.0.26100.6905

How to fix

Upgrade to a fixed version: Microsoft Windows Server 2016 10.0.14393.8524; Microsoft Windows Server 2019 10.0.17763.7922; Microsoft Windows Server 2022 10.0.20348.4297; Microsoft Windows Server 2022, 23H2 Edition (Server Core installation) 10.0.25398.1916; Microsoft Windows Server 2025 10.0.26100.6905. Check the vendor advisory for mitigations.

References

• https://msrc.microsoft.com/update-guide/vulnerability/CVE-2025-59287
• https://hawktrace.com/blog/CVE-2025-59287
• https://www.bleepingcomputer.com/news/security/cisa-orders-feds-to-patch-windows-server-wsus-flaw-exploited-in-attacks/
• https://www.vicarius.io/vsociety/posts/cve-2025-59287-detection-script-rce-vulnerability-in-windows-server-update-service
• https://www.vicarius.io/vsociety/posts/cve-2025-59287-mitigation-script-rce-vulnerability-in-windows-server-update-service
• https://gist.github.com/hawktrace/880b54fb9c07ddb028baaae401bd3951
• https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2025-59287

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