CVE-2023-28229
CVE-2023-28229 is a security flaw in Microsoft Windows CNG Key Isolation Service, a part of Windows, Microsoft’s operating system. Someone who already has a foothold can use Microsoft Windows CNG Key Isolation Service 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 4 Oct 2023.[1]
Microsoft Windows CNG Key Isolation Service 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 10.0.17763.4252, 10.0.20348.1668, 10.0.19042.2846 and 10.0.22000.1817 and others.
Description
CISA calls it a privilege escalation in Microsoft Windows CNG Key Isolation Service. In its words: “Microsoft Windows Cryptographic Next Generation (CNG) Key Isolation Service contains an unspecified vulnerability that allows an attacker to gain specific limited SYSTEM privileges.”[1]
The underlying weakness is CWE-591, in MITRE’s list of common software weaknesses.[2]
It scores 7.0 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 | 10.0.17763.4252 |
| Windows Server 2019 | 10.0.17763.4252 |
| Windows Server 2019 (Server Core installation) | 10.0.17763.4252 |
| Windows Server 2022 | 10.0.20348.1668 |
| Windows 10 Version 20H2 | 10.0.19042.2846 |
| Windows 11 version 21H2 | 10.0.22000.1817 |
| Windows 10 Version 21H2 | 10.0.19044.2846 |
| Windows 11 version 22H2 | 10.0.22621.1555 |
Every device with Microsoft Windows CNG Key Isolation Service needs the update.
Exploitation
CISA added it to its catalog of known exploited vulnerabilities on 4 Oct 2023, 176 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 25 Oct 2023 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 2%. That’s in the top 24% 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 mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable.”[1]
- Update Microsoft Windows CNG Key Isolation Service 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 10.0.17763.4252 or later.Fixed in version 10.0.17763.4252, 10.0.20348.1668, 10.0.19042.2846 and 10.0.22000.1817 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 |
|---|---|
| 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.[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 2%.[4] |
See also
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-2023-42793, JetBrains TeamCity: authentication bypass ·
Every Microsoft flaw on CISA’s list · Everything added in October 2023
References
- ^ Cybersecurity and Infrastructure Security Agency. “Microsoft Windows CNG Key Isolation Service Privilege Escalation Vulnerability”. Known Exploited Vulnerabilities Catalog, added 4 Oct 2023.
- ^ National Institute of Standards and Technology. “CVE-2023-28229 Detail”. National Vulnerability Database, published 11 Apr 2023.
- ^ Microsoft. Advisories and fixes: msrc.microsoft.com.
- ^ FIRST. “Exploit Prediction Scoring System”. EPSS 0.017, percentile 76.8, 31 Oct 2026.
- CVE Program. “CVE-2023-28229”. 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.