### 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](https://github.com/MessagePack-CSharp/MessagePack-CSharp/security/advisories/GHSA-7q36-4xx7-xcxf), which provided an inadequate fix for the hash collision part of the vulnerability. ### Patches The following steps are required to mitigate this risk. 1. Upgrade to a version of the library where a fix is available. 1. Review the steps in [this previous advisory](https://github.com/MessagePack-CSharp/MessagePack-CSharp/security/advisories/GHSA-7q36-4xx7-xcxf) to ensure you have your application configured for untrusted data. ### Workarounds If upgrading MessagePack to a patched version is not an option for you, you may apply a manual workaround …

Unmarshal can panic on some inputs, possibly allowing for denial of service attacks.

An issue was discovered in the messagepack-rs crate through 2021-01-26 for Rust. deserialize_string_primitive may read from uninitialized memory locations.

An issue was discovered in the messagepack-rs crate through 2021-01-26 for Rust. deserialize_extension_others may read from uninitialized memory locations.

An issue was discovered in the messagepack-rs crate through 2021-01-26 for Rust. deserialize_string may read from uninitialized memory locations.

An issue was discovered in the messagepack-rs crate through 2021-01-26 for Rust. deserialize_binary may read from uninitialized memory locations.

MessagePack for C# and Unity before version 1.9.11 and 2.1.90 has a vulnerability where untrusted data can lead to DoS attack due to hash collisions and stack overflow. Review the linked GitHub Security Advisory for more information and remediation steps.