CVE-2026-41715: Reactor Netty HTTP Client Credential Leak on Protocol Downgrade Redirect
Summary
CVE-2026-41715: Reactor Netty HTTP Client Leaks Credentials On Protocol Downgrade Redirect. Affects io.projectreactor.netty:reactor-netty across 4 version ranges.
>= 1.0.0, <= 1.0.48
>= 1.1.0, <= 1.1.31
>= 1.2.0, < 1.2.18
>= 1.3.0, < 1.3.6
Fixed in 1.2.18 or 1.3.6, depending on the release line you run. How to fix ↓
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Background
Reactor Netty is a foundational library for building reactive applications in Java, providing an asynchronous and non-blocking HTTP client and server. It is widely used for its performance and scalability in handling web requests. However, certain versions of Reactor Netty are vulnerable to a security issue that can lead to credential leakage during HTTP redirects from secure to insecure endpoints.
Vulnerability Detail
The vulnerability arises when the Reactor Netty HTTP client is configured to follow redirects. In specific scenarios, if a redirect occurs from a secure (HTTPS) endpoint to an insecure (HTTP) endpoint, the client may inadvertently leak sensitive credentials. This can expose users to unauthorized access and data breaches, especially if the credentials are intercepted by malicious actors. The affected versions include Reactor Netty 1.0.0 through 1.0.51, 1.1.0 through 1.1.35, 1.2.0 through 1.2.17, and 1.3.0 through 1.3.5.
How To Fix
Latest published version: 1.4.0-RC1 as of 23 Oct 2026
Upgrading to it may include breaking changes; the versions below are the minimum fixed release for this vulnerability.
If you can't move to the latest
The minimum fixed version depends on the release line you run.
-
>= 1.2.0, < 1.2.181.2.18 -
>= 1.3.0, < 1.3.61.3.6
Tip — Not sure which release line you're on? Vulert can find the fix for the version you are using. Scan free →
Workaround
As a temporary workaround, you can disable automatic redirect following in your HTTP client configuration. This can be done by setting the 'followRedirects' option to false, ensuring that your application does not inadvertently expose credentials during redirects.
Conclusion
The Reactor Netty HTTP client vulnerability (CVE-2026-41715) poses a risk of credential leakage during protocol downgrade redirects. It is crucial to update to the patched versions to mitigate this risk. Additionally, using tools like Vulert can help monitor and identify vulnerabilities in your applications effectively.
See every vulnerability recorded for io.projectreactor.netty:reactor-netty →
FAQ
CVE-2026-41715 is a vulnerability in the Reactor Netty HTTP client that can lead to credential leakage during HTTP redirects from secure to insecure endpoints.
Affected versions include Reactor Netty 1.0.0 through 1.0.51, 1.1.0 through 1.1.35, 1.2.0 through 1.2.17, and 1.3.0 through 1.3.5.
You can use Vulert, which monitors and alerts for open-source vulnerabilities in real-time using just your pom.xml. Visit the Vulert playground at Vulert Scanner to check for vulnerabilities without signup.
The CVSS score for this vulnerability is 6.1, indicating a moderate severity level.
If immediate updates are not possible, consider disabling automatic redirect following in your HTTP client configuration as a temporary workaround.
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