CVE-2025-59287
CVE-2025-59287 is a security flaw in Microsoft Windows, Microsoft’s operating system for PCs and servers. Attackers can run their own code on Microsoft Windows. The US Cybersecurity and Infrastructure Security Agency (CISA) added it to its catalog of flaws known to be used in attacks on 24 Oct 2025.[1]
Microsoft Windows is in things households have, such as phones, computers, browsers and everyday apps, so the fix matters at home as much as at work. Fixed in version 6.2.9200.25728, 6.3.9600.22826, 10.0.14393.8524 and 10.0.17763.7922.
Description
CISA calls it a server update service (WSUS) deserialization of untrusted data in Microsoft Windows. In its words: “Microsoft Windows Server Update Service (WSUS) contains a deserialization of untrusted data vulnerability that allows for remote code execution.”[1]
The underlying weakness is deserialization of untrusted data (CWE-502), in MITRE’s list of common software weaknesses.[2]
It scores 9.8 out of 10 on the Common Vulnerability Scoring System, which rates it critical, scored by the organisation that published the CVE using CVSS 3.1.[2]
Affected versions
NVD’s record lists these fixed versions: in each line, everything before the version shown is affected.[2]
| Product | Fixed in |
|---|---|
| Windows Server 2012 | 6.2.9200.25728 |
| Windows Server 2012 (Server Core installation) | 6.2.9200.25728 |
| Windows Server 2012 R2 | 6.3.9600.22826 |
| Windows Server 2012 R2 (Server Core installation) | 6.3.9600.22826 |
| Windows Server 2016 | 10.0.14393.8524 |
| Windows Server 2016 (Server Core installation) | 10.0.14393.8524 |
| Windows Server 2019 | 10.0.17763.7922 |
| Windows Server 2019 (Server Core installation) | 10.0.17763.7922 |
Every device with Microsoft Windows needs the update.
Exploitation
CISA added it to its catalog of known exploited vulnerabilities on 24 Oct 2025, 10 days after it was made public. CISA lists a flaw only when it has reliable evidence of it being exploited, and gave US federal agencies until 14 Nov 2025 to fix it.[1]
FIRST’s Exploit Prediction Scoring System, which estimates how likely a flaw is to be used in attacks in the next 30 days from what it sees across the internet, puts it at over 99%. That’s in the top 1% of the flaws it scores.[4]
CISA assesses it as automatable: attackers can run it against many targets at once.
CISA doesn’t say who was attacked, or how.
Fix
Microsoft has published a fix or advice.[3] CISA’s required action: “Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.”[1]
- Update Microsoft Windows now.On Windows: Settings, Windows Update, Check for updates, then restart. Office updates come the same way, or from any Office app: File, Account, Update Options. Then turn on automatic updates, so the next fix arrives on its own.
- Check you’re on 6.2.9200.25728 or later.Fixed in version 6.2.9200.25728, 6.3.9600.22826, 10.0.14393.8524 and 10.0.17763.7922. Anything older is what attackers are going after.
- If there’s no update, stop using it.CISA’s advice when a flaw being used in attacks has no fix is to stop using the product until it does.
Timeline
| Date | Event |
|---|---|
| The flaw is made public in the National Vulnerability Database, with a severity score of 9.8.[2] | |
| CISA adds it to its catalog of flaws known to be used in attacks.[1] | |
| CISA’s deadline for US government agencies to fix it.[1] | |
| FIRST puts the odds of it being used in attacks in the next 30 days at over 99%.[4] |
See also
Other Microsoft Windows flaws
- CVE-2026-96951: command injection ·
- CVE-2026-85880: heap-based buffer overflow ·
- CVE-2026-81963: link following ·
- CVE-2008-4250: buffer overflow ·
- CVE-2026-32202: protection mechanism failure ·
- CVE-2025-60710: link following ·
Other deserialization of untrusted data flaws
- CVE-2021-23758, Ajax.NET Professional: deserialization of untrusted data ·
- CVE-2026-63077, JetBrains TeamCity: deserialization of untrusted data ·
- CVE-2026-45247, Mirasvit Full Page Cache Warmer: full page cache warmer deserialization of untrusted data ·
- CVE-2026-20131, Cisco Secure Firewall Management Center (FMC): software and cisco security cloud control (SCC) firewall management deserialization of untrusted data ·
- CVE-2025-26399, SolarWinds Web Help Desk: deserialization of untrusted data ·
Added the same day
- CVE-2025-54236, Adobe Commerce and Magento: improper input validation ·
Every Microsoft flaw on CISA’s list · Everything added in October 2025
References
- ^ Cybersecurity and Infrastructure Security Agency. “Microsoft Windows Server Update Service (WSUS) Deserialization of Untrusted Data Vulnerability”. Known Exploited Vulnerabilities Catalog, added 24 Oct 2025.
- ^ National Institute of Standards and Technology. “CVE-2025-59287 Detail”. National Vulnerability Database, published 14 Oct 2025.
- ^ Microsoft. Advisories and fixes: msrc.microsoft.com, msrc.microsoft.com, vicarius.io.
- ^ FIRST. “Exploit Prediction Scoring System”. EPSS 1.000, percentile 100.0, 31 Oct 2026.
- CVE Program. “CVE-2025-59287”. The official CVE record.
This article is built from CISA’s catalog (version 2026.10.30), NVD’s record and FIRST’s scores, kept in HARD’s database and checked every morning. The plain English is HARD’s.