# CVE-2026-21525: Microsoft Windows NULL Pointer Dereference

> An unauthorized local attacker can cause a denial of service in Windows Remote Access Connection Manager via a null pointer dereference.

- **Severity:** Medium 6.2 (`CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H/E:U/RL:O/RC:C`)
- **Exploited in the wild:** Yes, since 10 Feb 2026 (CISA KEV)
- **Login needed:** Not needed
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 10 Feb 2026
- **Updated:** 19 Aug 2026
- **Also known as:** GHSA-cf8p-vhmm-h7g6

## What is CVE-2026-21525?

CVE-2026-21525 is a medium-severity vulnerability in Microsoft Windows 10 1607, published on 10 Feb 2026. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

Null pointer dereference in Windows Remote Access Connection Manager allows an unauthorized attacker to deny service locally.

Weakness: CWE-476 (NULL Pointer Dereference)

## Which versions are affected by CVE-2026-21525?

It affects 13 products.


Products: Microsoft Windows 10 1607, Microsoft Windows 10 1809, Microsoft Windows 10 21h2, Microsoft Windows 10 22h2, Microsoft Windows 11 23h2, Microsoft Windows 11 24h2, Microsoft Windows 11 25h2, Microsoft Windows Server 2012, Microsoft Windows Server 2016, Microsoft Windows Server 2019, Microsoft Windows Server 2022, Microsoft Windows Server 2022 23h2, Microsoft Windows Server 2025.

## How do I fix CVE-2026-21525?

No fix has been published for CVE-2026-21525 yet. Limit exposure of the affected software until one is available. US federal agencies must fix it by 3 Mar 2026.

## Is CVE-2026-21525 being exploited?

Yes. Attackers have exploited CVE-2026-21525 in the wild since at least 10 Feb 2026.

## Other vulnerabilities in Microsoft Windows 10 1607

- [CVE-2026-33824](https://insights.sbomify.com/CVE-2026-33824/): Microsoft Internet Key Exchange (IKE) Service Extensions Double Free (critical 9.8, exploited in the wild)
- [CVE-2026-21510](https://insights.sbomify.com/CVE-2026-21510/): Microsoft Windows Shell Protection Mechanism Failure (high 8.8, exploited in the wild)
- [CVE-2026-21513](https://insights.sbomify.com/CVE-2026-21513/): Microsoft MSHTML Framework Protection Mechanism Failure (high 8.8, exploited in the wild)
- [CVE-2023-32049](https://insights.sbomify.com/CVE-2023-32049/): Microsoft Windows Defender SmartScreen Security Feature Bypass (high 8.8, exploited in the wild)
- [CVE-2023-29360](https://insights.sbomify.com/CVE-2023-29360/): Microsoft Streaming Service Untrusted Pointer Dereference (high 8.4, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-21525 and fix it if it is affected.

What it is: CVE-2026-21525 is a medium-severity vulnerability in Microsoft Windows 10 1607, published on 10 Feb 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: Yes. Attackers have exploited CVE-2026-21525 in the wild since at least 10 Feb 2026.

Affected product: Microsoft Windows 10 1607. 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-2026-21525/ (Markdown: https://insights.sbomify.com/CVE-2026-21525/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-21525
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-21525
- OSV: https://osv.dev/vulnerability/CVE-2026-21525

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-21525/
Summaries are generated and may contain mistakes; the official description above is the record.