CVE-2016-3309
CVE-2016-3309 is a security flaw in Microsoft Windows, Microsoft’s operating system for PCs and servers. Someone who already has a way in can use Microsoft Windows to run their own code. The US Cybersecurity and Infrastructure Security Agency (CISA) added it to its catalog of flaws known to be used in attacks on 15 Mar 2022, and says ransomware gangs have used it.[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. Microsoft has published a fix or advice.
Description
CISA calls it a kernel privilege escalation in Microsoft Windows. In its words: “A privilege escalation vulnerability exists when the Windows kernel fails to properly handle objects in memory. An attacker who successfully exploited this vulnerability could run arbitrary code in kernel mode.”[1]
The CVE record adds: “The kernel-mode drivers in Microsoft Windows Vista SP2; Windows Server 2008 SP2 and R2 SP1; Windows 7 SP1; Windows 8.1; Windows Server 2012 Gold and R2; Windows RT 8.1; and Windows 10 Gold, 1511, and 1607 allow local users to gain privileges via a crafted application, aka "Win32k Elevation of Privilege Vulnerability," a different vulnerability than CVE-2016-3308, CVE-2016-3310, and CVE-2016-3311.”[2]
The underlying weakness is permissions and access control (CWE-264), 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 Windows.
Every device with Microsoft Windows needs the update.
Exploitation
CISA added it to its catalog of known exploited vulnerabilities on 15 Mar 2022, 2,044 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 5 Apr 2022 to fix it.[1] CISA says ransomware gangs have used it.
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 20%. That’s in the top 3% 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]
- 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.
- 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 7.8.[2] | |
| CISA adds it to its catalog of flaws known to be used in attacks, noting that ransomware gangs have used it.[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 20%.[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 permissions and access control flaws
- CVE-2015-3246, Red Hat Libuser: race condition ·
- CVE-2013-0643, Adobe Flash Player: incorrect default permissions ·
- CVE-2015-0310, Adobe Flash Player: ASLR bypass ·
- CVE-2013-3993, IBM InfoSphere BigInsights: invalid input ·
- CVE-2013-0422, Oracle Java Runtime Environment (JRE): JRE remote code execution ·
Added the same day
- CVE-2020-5135, SonicWall SonicOS: buffer overflow ·
- CVE-2019-1405, Microsoft Windows: universal plug and play (UPnP) service privilege escalation ·
- CVE-2019-1322, Microsoft Windows: privilege escalation ·
- CVE-2019-1315, Microsoft Windows: error reporting manager privilege escalation ·
- CVE-2019-1253, Microsoft Windows: appX deployment server privilege escalation ·
Every Microsoft flaw on CISA’s list · Everything added in March 2022
References
- ^ Cybersecurity and Infrastructure Security Agency. “Microsoft Windows Kernel Privilege Escalation Vulnerability”. Known Exploited Vulnerabilities Catalog, added 15 Mar 2022.
- ^ National Institute of Standards and Technology. “CVE-2016-3309 Detail”. National Vulnerability Database, published 9 Aug 2016.
- ^ Microsoft. Advisories and fixes: docs.microsoft.com.
- ^ FIRST. “Exploit Prediction Scoring System”. EPSS 0.205, percentile 97.5, 31 Oct 2026.
- CVE Program. “CVE-2016-3309”. 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.