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CVE-2018-8120

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-2018-8120 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 15 Mar 2022, and says ransomware gangs have used it.[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: “A privilege escalation vulnerability exists in Windows when the Win32k component fails to properly handle objects in memory.”[1]

The CVE record adds: “An elevation of privilege vulnerability exists in Windows when the Win32k component fails to properly handle objects in memory, aka "Win32k Elevation of Privilege Vulnerability." This affects Windows Server 2008, Windows 7, Windows Server 2008 R2. This CVE ID is unique from CVE-2018-8124, CVE-2018-8164, CVE-2018-8166.”[2]

The underlying weakness is CWE-404, in MITRE’s list of common software weaknesses.

It scores 7.0 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 15 Mar 2022, 1,406 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 73%. That’s in the top 1% 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 7.0.[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 73%.[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 ·

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

  1. ^ Cybersecurity and Infrastructure Security Agency. “Microsoft Win32k Privilege Escalation Vulnerability”. Known Exploited Vulnerabilities Catalog, added 15 Mar 2022.
  2. ^ National Institute of Standards and Technology. “CVE-2018-8120 Detail”. National Vulnerability Database, published 9 May 2018.
  3. ^ Microsoft. Advisories and fixes: portal.msrc.microsoft.com.
  4. ^ FIRST. “Exploit Prediction Scoring System”. EPSS 0.733, percentile 99.5, 31 Oct 2026.
  5. CVE Program. “CVE-2018-8120”. 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.