# CVE-2021-43215: iSNS Server Memory Corruption Vulnerability Can Lead to Remote Code Execution

> A memory corruption vulnerability in the Windows iSNS Server allows remote attackers to execute arbitrary code.

- **Severity:** Critical 9.8 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 15 Dec 2021
- **Updated:** 4 Aug 2024
- **Also known as:** GHSA-f369-x9m4-pmxp

## What is CVE-2021-43215?

CVE-2021-43215 is a critical memory corruption vulnerability in Microsoft Windows 10, published on 15 Dec 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

iSNS Server Memory Corruption Vulnerability Can Lead to Remote Code Execution

Weakness: CWE-787 (Out-of-bounds Write)

## Which versions are affected by CVE-2021-43215?

It affects 10 products.


Products: Microsoft Windows 10, Microsoft Windows 11, Microsoft Windows 7, Microsoft Windows 8.1, Microsoft Windows Rt 8.1, Microsoft Windows Server, Microsoft Windows Server 2008, Microsoft Windows Server 2012, Microsoft Windows Server 2016, Microsoft Windows Server 2019.

## How do I fix CVE-2021-43215?

No fix has been published for CVE-2021-43215 yet. Limit exposure of the affected software until one is available.

## Is CVE-2021-43215 being exploited?

There is no known exploitation of CVE-2021-43215 in the wild and no public exploit code.

## Other vulnerabilities in Microsoft Windows 10

- [CVE-2015-2426](https://insights.sbomify.com/CVE-2015-2426/): Microsoft Windows Adobe Type Manager Library Remote Code Execution (high 8.8, exploited in the wild)
- [CVE-2015-1769](https://insights.sbomify.com/CVE-2015-1769/): Microsoft Windows Mount Manager Privilege Escalation (medium 6.6, exploited in the wild)
- [CVE-2020-1467](https://insights.sbomify.com/CVE-2020-1467/): Windows Hard Link Elevation of Privilege Vulnerability (critical 10.0)
- [CVE-2021-26424](https://insights.sbomify.com/CVE-2021-26424/): Windows TCP/IP Remote Code Execution Vulnerability (critical 9.9)
- [CVE-2021-28476](https://insights.sbomify.com/CVE-2021-28476/): Windows Hyper-V Remote Code Execution Vulnerability (critical 9.9)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-43215 and fix it if it is affected.

What it is: CVE-2021-43215 is a critical memory corruption vulnerability in Microsoft Windows 10, published on 15 Dec 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2021-43215 in the wild and no public exploit code.

Affected product: Microsoft Windows 10. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2021-43215/ (Markdown: https://insights.sbomify.com/CVE-2021-43215/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-43215
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-43215
- OSV: https://osv.dev/vulnerability/CVE-2021-43215

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-43215/
Summaries are generated and may contain mistakes; the official description above is the record.