CVE-2022-24521
CVE-2022-24521 is a security flaw in Microsoft Windows, Microsoft’s operating system for PCs and servers. Someone who already has a foothold can use Microsoft Windows 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 13 Apr 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. Fixed in version 10.0.17763.2803, 10.0.18363.2212, 10.0.19043.1645 and 10.0.20348.643 and others.
Description
CISA calls it a CLFS driver privilege escalation in Microsoft Windows. In its words: “Microsoft Windows Common Log File System (CLFS) Driver contains an unspecified vulnerability that allows for privilege escalation.”[1]
The underlying weakness is out-of-bounds write (CWE-787), CWE-1285, in MITRE’s list of common software weaknesses.[2]
It scores 7.8 out of 10 on the Common Vulnerability Scoring System, which rates it high, 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 10 Version 1809 | 10.0.17763.2803 |
| Windows Server 2019 | 10.0.17763.2803 |
| Windows Server 2019 (Server Core installation) | 10.0.17763.2803 |
| Windows 10 Version 1909 | 10.0.18363.2212 |
| Windows 10 Version 21H1 | 10.0.19043.1645 |
| Windows Server 2022 | 10.0.20348.643 |
| Windows 10 Version 20H2 | 10.0.19042.1645 |
| Windows Server version 20H2 | 10.0.19042.1645 |
Every device with Microsoft Windows needs the update.
Exploitation
CISA added it to its catalog of known exploited vulnerabilities on 13 Apr 2022. CISA lists a flaw only when it has reliable evidence of it being exploited, and gave US federal agencies until 4 May 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 7%. That’s in the top 6% 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.
- Check you’re on 10.0.17763.2803 or later.Fixed in version 10.0.17763.2803, 10.0.18363.2212, 10.0.19043.1645 and 10.0.20348.643 and others. 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 |
|---|---|
| CISA adds it to its catalog of flaws known to be used in attacks, noting that ransomware gangs have used it.[1] | |
| The flaw is made public in the National Vulnerability Database, with a severity score of 7.8.[2] | |
| 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 7%.[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 out-of-bounds write flaws
- CVE-2026-86950, Apple devices: out-of-bounds write ·
- CVE-2026-53266, Linux Kernel: out-of-bounds write ·
- CVE-2026-87491, Chrome and other Chromium browsers: out of bounds write ·
- CVE-2026-53362, Linux Kernel: unspecified ·
- CVE-2022-0995, Linux Kernel: out-of-bounds write ·
Added the same day
- CVE-2018-7602, Drupal Core: remote code execution ·
- CVE-2018-20753, Kaseya Virtual System/Server Administrator (VSA): VSA remote code execution ·
- CVE-2015-5123, Adobe Flash Player: use-after-free ·
- CVE-2015-5122, Adobe Flash Player: use-after-free ·
- CVE-2015-3113, Adobe Flash Player: heap-based buffer overflow ·
Every Microsoft flaw on CISA’s list · Everything added in April 2022
References
- ^ Cybersecurity and Infrastructure Security Agency. “Microsoft Windows CLFS Driver Privilege Escalation Vulnerability”. Known Exploited Vulnerabilities Catalog, added 13 Apr 2022.
- ^ National Institute of Standards and Technology. “CVE-2022-24521 Detail”. National Vulnerability Database, published 15 Apr 2022.
- ^ Microsoft. Advisories and fixes: msrc.microsoft.com.
- ^ FIRST. “Exploit Prediction Scoring System”. EPSS 0.071, percentile 94.3, 31 Oct 2026.
- CVE Program. “CVE-2022-24521”. 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.