Summary
MessagePack allows untrusted data to lead to DoS attack due to hash collisions and stack overflow
Workarounds
If upgrading MessagePack to a patched version is not an option for you, you may apply a manual workaround as follows:
- Declare a class that derives from
MessagePackSecurity. - Override the
GetHashCollisionResistantEqualityComparer<T>method to provide a collision-resistant hash function of your own and avoid callingbase.GetHashCollisionResistantEqualityComparer<T>(). - Configure a
MessagePackSerializerOptionswith an instance of your derived type by callingWithSecurityon an existing options object. - Use your custom options object for all deserialization operations. This may be by setting the
MessagePackSerializer.DefaultOptionsstatic property, if you call methods that rely on this default property, and/or by passing in the options object explicitly to anyDeserializemethod.
References
- Learn more about best security practices when reading untrusted data with MessagePack 1.x or MessagePack 2.x.
- The .NET team's discussion on hash collision vulnerabilities of their
HashCodestruct (or in the pull request that merges this into the dotnet org).
For more information
If you have any questions or comments about this advisory:
Impact
When this library is used to deserialize messagepack data from an untrusted source, there is a risk of a denial of service attack by an attacker that sends data contrived to produce hash collisions, leading to large CPU consumption disproportionate to the size of the data being deserialized.
This is similar to a prior advisory, which provided an inadequate fix for the hash collision part of the vulnerability.
Affected versions
Security releases
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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See it in your environmentNew to Kodem? Get a demo →Remediation advice
The following steps are required to mitigate this risk.
- Upgrade to a version of the library where a fix is available. If upgrading from v1, check out our migration guide.
- Review the steps in this previous advisory to ensure you have your application configured for untrusted data.
Frequently Asked Questions
- What is CVE-2024-48924? CVE-2024-48924 is a medium-severity security vulnerability in MessagePack (nuget), affecting versions < 2.5.187. It is fixed in 2.5.187, 3.0.214-rc.1.
- Which versions of MessagePack are affected by CVE-2024-48924? MessagePack (nuget) versions < 2.5.187 is affected.
- Is there a fix for CVE-2024-48924? Yes. CVE-2024-48924 is fixed in 2.5.187, 3.0.214-rc.1. Upgrade to this version or later.
- Is CVE-2024-48924 exploitable, and should I be worried? Whether CVE-2024-48924 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 CVE-2024-48924 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 CVE-2024-48924?
- Upgrade
MessagePackto 2.5.187 or later - Upgrade
MessagePackto 3.0.214-rc.1 or later
- Upgrade