# CVE-2019-1126: Security feature bypass in Windows Server

> An attacker can bypass ADFS extranet lockout policies to launch brute-force attacks or cause account lockouts in Active Directory.

- **Severity:** Medium 5.3 (`CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 29 Jul 2019
- **Updated:** 4 Aug 2024
- **Also known as:** GHSA-7f55-8m7r-49x9

## What is CVE-2019-1126?

CVE-2019-1126 is a medium-severity vulnerability in Microsoft Windows Server 2012, published on 29 Jul 2019. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

A security feature bypass vulnerability exists in Active Directory Federation Services (ADFS) which could allow an attacker to bypass the extranet lockout policy.To exploit this vulnerability, an attacker could run a specially crafted application, which would allow an attacker to launch a password brute-force attack or cause account lockouts in Active Directory.This security update corrects how ADFS handles external authentication requests., aka 'ADFS Security Feature Bypass Vulnerability'. This CVE ID is unique from CVE-2019-0975.

Weakness: CWE-307 (Improper Restriction of Excessive Authentication Attempts)

## Which versions are affected by CVE-2019-1126?

It affects 3 products.


Products: Microsoft Windows Server 2012, Microsoft Windows Server 2016, Microsoft Windows Server 2019.

## How do I fix CVE-2019-1126?

No fix has been published for CVE-2019-1126 yet. Limit exposure of the affected software until one is available.

## Is CVE-2019-1126 being exploited?

There is no known exploitation of CVE-2019-1126 in the wild and no public exploit code.

## Other vulnerabilities in Microsoft Windows Server 2012

- [CVE-2025-59287](https://insights.sbomify.com/CVE-2025-59287/): Microsoft Windows Server Update Service (WSUS) Deserialization of Untrusted Data (critical 9.8, exploited in the wild)
- [CVE-2026-69595](https://insights.sbomify.com/CVE-2026-69595/): Windows Services for NFS ONCRPC XDR Driver Remote Code Execution Vulnerability (critical 9.8)
- [CVE-2026-78445](https://insights.sbomify.com/CVE-2026-78445/): Windows Services for NFS ONCRPC XDR Driver Remote Code Execution Vulnerability (critical 9.8)
- [CVE-2026-41089](https://insights.sbomify.com/CVE-2026-41089/): Windows Netlogon Remote Code Execution Vulnerability (critical 9.8)
- [CVE-2024-43639](https://insights.sbomify.com/CVE-2024-43639/): Windows KDC Proxy Remote Code Execution Vulnerability (critical 9.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2019-1126 and fix it if it is affected.

What it is: CVE-2019-1126 is a medium-severity vulnerability in Microsoft Windows Server 2012, published on 29 Jul 2019. 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-2019-1126 in the wild and no public exploit code.

Affected product: Microsoft Windows Server 2012. 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-2019-1126/ (Markdown: https://insights.sbomify.com/CVE-2019-1126/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2019-1126
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2019-1126
- OSV: https://osv.dev/vulnerability/CVE-2019-1126

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From sbomify Insights: https://insights.sbomify.com/CVE-2019-1126/
Summaries are generated and may contain mistakes; the official description above is the record.