CVE-2025-68121: Golang Package Vulnerability in Crypto/TLS Session Resumption
Summary
CVE-2025-68121: Unexpected session resumption in crypto/tls. Affects golang across 2 version ranges.
< 1.24.13
>= 1.25.0-0, < 1.25.7
Fixed in 1.24.13 or 1.25.7, depending on the release line you run. How to fix ↓
Also tracked for
The same CVE-2025-68121 is tracked separately for each ecosystem and vendor. Its fix information is the same; the package and affected versions differ.
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Background
Golang, also known as Go, is an open-source programming language designed for simplicity and efficiency in software development. It is widely used for building web servers, data pipelines, and other applications. The crypto/tls package in Golang provides support for TLS (Transport Layer Security), which is essential for secure communications over a computer network. However, a vulnerability has been identified that affects session resumption, potentially compromising the security of connections.
Vulnerability Detail
The vulnerability arises during session resumption in the crypto/tls package. If the Config object used for the initial handshake has its ClientCAs or RootCAs fields altered between the initial and resumed handshake, the resumed handshake may succeed incorrectly. This can occur if a user clones the Config and modifies the returned object or uses Config.GetConfigForClient. As a result, a client may resume a session with a server that it should not have been able to, or vice versa, leading to potential security breaches.
How To Fix
Fixed versions by release line
The minimum fixed version depends on the release line you run.
-
< 1.24.131.24.13 -
>= 1.25.0-0, < 1.25.71.25.7
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, avoid mutating the ClientCAs or RootCAs fields of the Config object after the initial handshake. Ensure that the same configuration is used for both the initial and resumed handshakes to prevent unintended session resumption.
Conclusion
CVE-2025-68121 highlights a significant vulnerability in the Golang crypto/tls package that can lead to unauthorized session resumption. It is essential for developers to update to the patched versions to ensure the security of their applications. By following the recommended steps and utilizing tools like Vulert, developers can effectively monitor and mitigate vulnerabilities in their software.
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FAQ
CVE-2025-68121 is a vulnerability in the Golang crypto/tls package that allows for unexpected session resumption, potentially compromising secure communications.
You can use Vulert's playground at Vulert Scanner to check if your application is affected by this vulnerability without needing to sign up.
The vulnerability affects all versions prior to 1.24.13 and 1.25.7. It is crucial to update to these versions or later.
If exploited, this vulnerability could allow unauthorized session resumption, leading to data breaches or unauthorized access to sensitive information.
Yes, you can avoid mutating the ClientCAs or RootCAs fields of the Config object after the initial handshake as a temporary workaround.
References
Related vulnerabilities
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