What is GHSA-6V7P-G79W-8964?

GHSA-6V7P-G79W-8964 is a high-severity use after free vulnerability in msgpack (pip), affecting versions <= 1.2.0. It is fixed in 1.2.1. Memory is accessed after it has been freed, leading to undefined behavior in native code.

How severe is GHSA-6V7P-G79W-8964?

GHSA-6V7P-G79W-8964 has a CVSS score of 7.5 (High). 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 msgpack are affected by GHSA-6V7P-G79W-8964?

msgpack (pip) versions <= 1.2.0 is affected.

Is there a fix for GHSA-6V7P-G79W-8964?

Yes. GHSA-6V7P-G79W-8964 is fixed in 1.2.1. Upgrade to this version or later.

Is GHSA-6V7P-G79W-8964 exploitable, and should I be worried?

Whether GHSA-6V7P-G79W-8964 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-6V7P-G79W-8964 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-6V7P-G79W-8964?

Upgrade msgpack to 1.2.1 or later.

GHSA-6V7P-G79W-8964 in msgpack

Q: How severe is GHSA-6V7P-G79W-8964?

GHSA-6V7P-G79W-8964 has a CVSS score of 7.5 (High). 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 msgpack are affected by GHSA-6V7P-G79W-8964?

msgpack (pip) versions <= 1.2.0 is affected.

Q: Is there a fix for GHSA-6V7P-G79W-8964?

Yes. GHSA-6V7P-G79W-8964 is fixed in 1.2.1. Upgrade to this version or later.

Q: Is GHSA-6V7P-G79W-8964 exploitable, and should I be worried?

Whether GHSA-6V7P-G79W-8964 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-6V7P-G79W-8964 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-6V7P-G79W-8964?

Upgrade msgpack to 1.2.1 or later.

Summary

MessagePack for Python: Out-of-bounds read / crash on Unpacker reuse after a caught error

Workarounds

Users should create a new Unpacker instead of reusing the same Unpacker after an error occurs.

Applying the above patch can prevent SEGV, but reusing the Streaming Unpacker after it has encountered an error will not yield correct data. If an error occurs during Streaming Unpacking, the Stream and Streaming Unpacker should be discarded.

Therefore, this is not just a workaround but the correct solution. The above patch only prevents crashes from incorrect usage.

Impact

If the Unpacker is used repeatedly after an error occurs, the process may crash with a SEGV.

If the Unpacker is used repeatedly to unpack untrusted input from external sources, it may be vulnerable to a DoS attack.

Memory is accessed after it has been freed, leading to undefined behavior in native code. Typical impact: memory corruption, crash, or potential code execution.

GHSA-6V7P-G79W-8964 has a CVSS score of 7.5 (High). The vector is network-reachable, no privileges required, and no user interaction. 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 (1.2.1); upgrading removes the vulnerable code path.

Affected versions

msgpack (<= 1.2.0)

Security releases

msgpack → 1.2.1 (pip)

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

v1.2.1

Frequently Asked Questions

What is GHSA-6V7P-G79W-8964? GHSA-6V7P-G79W-8964 is a high-severity use after free vulnerability in msgpack (pip), affecting versions <= 1.2.0. It is fixed in 1.2.1. Memory is accessed after it has been freed, leading to undefined behavior in native code.
How severe is GHSA-6V7P-G79W-8964? GHSA-6V7P-G79W-8964 has a CVSS score of 7.5 (High). 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 msgpack are affected by GHSA-6V7P-G79W-8964? msgpack (pip) versions <= 1.2.0 is affected.
Is there a fix for GHSA-6V7P-G79W-8964? Yes. GHSA-6V7P-G79W-8964 is fixed in 1.2.1. Upgrade to this version or later.
Is GHSA-6V7P-G79W-8964 exploitable, and should I be worried? Whether GHSA-6V7P-G79W-8964 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-6V7P-G79W-8964 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-6V7P-G79W-8964? Upgrade msgpack to 1.2.1 or later.