What is GHSA-C8M5-C952-6CM4?

GHSA-C8M5-C952-6CM4 is a medium-severity security vulnerability in rustls (rust), affecting versions < 0.23.46. It is fixed in 0.23.46, 0.24.0-dev.2.

How severe is GHSA-C8M5-C952-6CM4?

GHSA-C8M5-C952-6CM4 has a CVSS score of 4.0 (Medium). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.

Which versions of rustls are affected by GHSA-C8M5-C952-6CM4?

rustls (rust) versions < 0.23.46 is affected.

Is there a fix for GHSA-C8M5-C952-6CM4?

Yes. GHSA-C8M5-C952-6CM4 is fixed in 0.23.46, 0.24.0-dev.2. Upgrade to this version or later.

Is GHSA-C8M5-C952-6CM4 exploitable, and should I be worried?

Whether GHSA-C8M5-C952-6CM4 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk.

What actually determines whether GHSA-C8M5-C952-6CM4 is exploitable, and how bad it is?

Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.

How do I fix GHSA-C8M5-C952-6CM4?

Upgrade: rustls to 0.23.46 or later, rustls to 0.24.0-dev.2 or later.

GHSA-C8M5-C952-6CM4 in rustls

Q: How severe is GHSA-C8M5-C952-6CM4?

GHSA-C8M5-C952-6CM4 has a CVSS score of 4.0 (Medium). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.

Q: Which versions of rustls are affected by GHSA-C8M5-C952-6CM4?

rustls (rust) versions < 0.23.46 is affected.

Q: Is there a fix for GHSA-C8M5-C952-6CM4?

Yes. GHSA-C8M5-C952-6CM4 is fixed in 0.23.46, 0.24.0-dev.2. Upgrade to this version or later.

Q: Is GHSA-C8M5-C952-6CM4 exploitable, and should I be worried?

Whether GHSA-C8M5-C952-6CM4 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk.

Q: What actually determines whether GHSA-C8M5-C952-6CM4 is exploitable, and how bad it is?

Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.

Q: How do I fix GHSA-C8M5-C952-6CM4?

Upgrade: rustls to 0.23.46 or later, rustls to 0.24.0-dev.2 or later.

Summary

Rustls: Session Debug formatting exposes TLS master secrets and resumption PSKs

Formatting a client session value with Debug exposes its TLS 1.2 master secret or TLS 1.3 resumption PSK. A custom session store that logs these values can disclose keys to readers of the logs. Ordinary connection and built-in cache diagnostics remain redacted, and the session-store interface already warns that its values are sensitive.

Details

Derived formatters traverse the session's secret-bearing fields. This conflicts with the project's explicit key-material redaction policy.

Proof of concept

Custom ClientSessionStore implementations could leak secret data by using the provided Tls12ClientSessionValue or Tls13ClientSessionValue in a way that triggers its implementation of the Debug trait.

Acknowledgement

Thanks to OpenAI [email protected] for the disclosure.

Impact

Such store implementations could leak the master secret for the TLS connection.

GHSA-C8M5-C952-6CM4 has a CVSS score of 4.0 (Medium). The vector is requires local access, high privileges required, and user interaction required. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (0.23.46, 0.24.0-dev.2); upgrading removes the vulnerable code path.

Affected versions

rustls (< 0.23.46) rustls (>= 0.24.0-dev.1, < 0.24.0-dev.2)

Security releases

rustls → 0.23.46 (rust) rustls → 0.24.0-dev.2 (rust)

Kodem intelligence

Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.

Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.

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Remediation advice

Upgrade the following packages to resolve this vulnerability:

rustls to 0.23.46 or later; rustls to 0.24.0-dev.2 or later

Kodem Kai can prioritize this vulnerability in your dependency tree and generate a fix recommendation.

Frequently Asked Questions

What is GHSA-C8M5-C952-6CM4? GHSA-C8M5-C952-6CM4 is a medium-severity security vulnerability in rustls (rust), affecting versions < 0.23.46. It is fixed in 0.23.46, 0.24.0-dev.2.
How severe is GHSA-C8M5-C952-6CM4? GHSA-C8M5-C952-6CM4 has a CVSS score of 4.0 (Medium). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
Which versions of rustls are affected by GHSA-C8M5-C952-6CM4? rustls (rust) versions < 0.23.46 is affected.
Is there a fix for GHSA-C8M5-C952-6CM4? Yes. GHSA-C8M5-C952-6CM4 is fixed in 0.23.46, 0.24.0-dev.2. Upgrade to this version or later.
Is GHSA-C8M5-C952-6CM4 exploitable, and should I be worried? Whether GHSA-C8M5-C952-6CM4 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
What actually determines whether GHSA-C8M5-C952-6CM4 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
How do I fix GHSA-C8M5-C952-6CM4?
- Upgrade rustls to 0.23.46 or later
- Upgrade rustls to 0.24.0-dev.2 or later

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