CVE-2023-36424
CVE-2023-36424 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 2026.[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 10.0.22631.2715, 10.0.25398.531, 10.0.17763.5122 and 10.0.20348.2113 and others.
Description
CISA calls it an out-of-bounds read in Microsoft Windows. In its words: “Microsoft Windows Common Log File System Driver contains an out-of-bounds read vulnerability that could allow a threat actor for privileges escalation”[1]
The underlying weakness is out-of-bounds read (CWE-125), 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 NVD 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 11 version 22H3 | 10.0.22631.2715 |
| Windows Server 2022, 23H2 Edition (Server Core installation) | 10.0.25398.531 |
| Windows 11 Version 23H2 | 10.0.22631.2715 |
| Windows 10 Version 1809 | 10.0.17763.5122 |
| Windows Server 2019 | 10.0.17763.5122 |
| Windows Server 2019 (Server Core installation) | 10.0.17763.5122 |
| Windows Server 2022 | 10.0.20348.2113 |
| Windows 11 version 21H2 | 10.0.22000.2600 |
Every device with Microsoft Windows needs the update.
Exploitation
CISA added it to its catalog of known exploited vulnerabilities on 13 Apr 2026, 881 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 27 Apr 2026 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 12%. That’s in the top 4% 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, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.”[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 10.0.22631.2715 or later.Fixed in version 10.0.22631.2715, 10.0.25398.531, 10.0.17763.5122 and 10.0.20348.2113 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 7.8.[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 12%.[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 read flaws
- CVE-2026-3055, Citrix NetScaler: out-of-bounds read ·
- CVE-2025-5777, Citrix NetScaler ADC and Gateway: out-of-bounds read ·
- CVE-2025-5419, Chrome and other Chromium browsers: out-of-bounds read and write ·
- CVE-2024-53150, Linux Kernel: out-of-bounds read ·
- CVE-2025-22226, VMware ESXi, Workstation, and Fusion: information disclosure ·
Added the same day
- CVE-2026-34621, Adobe Acrobat and Reader: prototype pollution ·
- CVE-2026-21643, Fortinet FortiClient EMS: SQL injection ·
- CVE-2025-60710, Microsoft Windows: link following ·
- CVE-2023-21529, Microsoft Exchange Server: deserialization of untrusted data ·
- CVE-2020-9715, Adobe Acrobat: use-after-free ·
Every Microsoft flaw on CISA’s list · Everything added in April 2026
References
- ^ Cybersecurity and Infrastructure Security Agency. “Microsoft Windows Out-of-Bounds Read Vulnerability”. Known Exploited Vulnerabilities Catalog, added 13 Apr 2026.
- ^ National Institute of Standards and Technology. “CVE-2023-36424 Detail”. National Vulnerability Database, published 14 Nov 2023.
- ^ Microsoft. Advisories and fixes: msrc.microsoft.com, msrc.microsoft.com.
- ^ FIRST. “Exploit Prediction Scoring System”. EPSS 0.121, percentile 96.1, 31 Oct 2026.
- CVE Program. “CVE-2023-36424”. 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.