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CVE-2017-0263

From Exploited flaws, HARD’s guide to the flaws being used in attacks · Checked
This article is about a flaw in Microsoft Win32k. For every flaw being used in attacks, see Exploited flaws; for Microsoft’s, see Microsoft flaws being used in attacks.

CVE-2017-0263 is a security flaw in Microsoft Win32k, a part of Windows, Microsoft’s operating system. Someone who already has a foothold can use Microsoft Win32k to take full control of the machine. The US Cybersecurity and Infrastructure Security Agency (CISA) added it to its catalog of flaws known to be used in attacks on 10 Feb 2022.[1]

Microsoft Win32k is in things households have, such as phones, computers, browsers and everyday apps, so the fix matters at home as much as at work. Microsoft has published a fix or advice.

Description

CISA calls it a privilege escalation in Microsoft Win32k. In its words: “Microsoft Win32k contains a privilege escalation vulnerability due to the Windows kernel-mode driver failing to properly handle objects in memory.”[1]

The CVE record adds: “The kernel-mode drivers in Microsoft Windows Server 2008 SP2 and R2 SP1, Windows 7 SP1, Windows 8.1, Windows Server 2012 Gold and R2, Windows RT 8.1, Windows 10 Gold, 1511, 1607, 1703, and Windows Server 2016 allow local users to gain privileges via a crafted application, aka "Win32k Elevation of Privilege Vulnerability."”[2]

The underlying weakness is use after free (CWE-416), in MITRE’s list of common software weaknesses.

It scores 7.8 out of 10 on the Common Vulnerability Scoring System, which rates it high, scored by NVD using CVSS 3.1.[2]

Affected versions

NVD’s record doesn’t list version ranges for it; Microsoft’s advisory has them[3]. CISA names the product as Microsoft Win32k.

Every device with Microsoft Win32k needs the update.

Exploitation

CISA added it to its catalog of known exploited vulnerabilities on 10 Feb 2022, 1,735 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 10 Aug 2022 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 10%. That’s in the top 5% of the flaws it scores.[4]

CISA assesses it as not automatable: each attack takes some work.

CISA doesn’t say who was attacked, or how.

Fix

Microsoft has published a fix or advice.[3] CISA’s required action: “Apply updates per vendor instructions.”[1]

  1. Update Microsoft Win32k 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.
  2. 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

DateEvent
The flaw is made public in the National Vulnerability Database, with a severity score of 7.8.[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 10%.[4]

See also

Other Microsoft Win32k flaws

Other Microsoft flaws

  • CVE-2026-96951, Microsoft Windows: command injection ·
  • CVE-2026-65660, Microsoft SharePoint: code injection ·
  • CVE-2026-85880, Microsoft Windows: heap-based buffer overflow ·
  • CVE-2026-81963, Microsoft Windows: link following ·
  • CVE-2019-1068, Microsoft SQL Server: remote code execution ·

Other use after free flaws

Added the same day

  • CVE-2021-36934, Microsoft Windows: SAM local privilege escalation ·
  • CVE-2020-0796, Microsoft SMBv3: remote code execution ·
  • CVE-2018-1000861, Jenkins Stapler Web Framework: stapler web framework deserialization of untrusted data ·
  • CVE-2017-9791, Apache Struts 1: improper input validation ·
  • CVE-2017-8464, Microsoft Windows: shell (.lnk) remote code execution ·

Every Microsoft flaw on CISA’s list · Everything added in February 2022

References

  1. ^ Cybersecurity and Infrastructure Security Agency. “Microsoft Win32k Privilege Escalation Vulnerability”. Known Exploited Vulnerabilities Catalog, added 10 Feb 2022.
  2. ^ National Institute of Standards and Technology. “CVE-2017-0263 Detail”. National Vulnerability Database, published 12 May 2017.
  3. ^ Microsoft. Advisories and fixes: portal.msrc.microsoft.com.
  4. ^ FIRST. “Exploit Prediction Scoring System”. EPSS 0.100, percentile 95.6, 31 Oct 2026.
  5. CVE Program. “CVE-2017-0263”. 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.