{"id":"CVE-2020-5234","aliases":["GHSA-7q36-4xx7-xcxf"],"url":"https://o3.security/vulnerability/CVE-2020-5234","summary":"Untrusted data can lead to DoS attack due to hash collisions and stack overflow in MessagePack","details":"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.","published":"2020-01-31T18:15:11.860Z","modified":"2026-08-27T08:40:28.601814Z","cvss":{"score":6.5,"severity":"MEDIUM","vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H"},"epss":null,"cisaKev":null,"exploitsKnown":null,"affectedPackages":[{"ecosystem":"NuGet","name":"MessagePack","fixedVersion":"1.9.11"},{"ecosystem":"NuGet","name":"MessagePack","fixedVersion":"2.1.90"},{"ecosystem":"NuGet","name":"MessagePack.ImmutableCollection","fixedVersion":"1.9.11"},{"ecosystem":"NuGet","name":"MessagePack.ImmutableCollection","fixedVersion":"2.1.90"},{"ecosystem":"NuGet","name":"MessagePack.ReactiveProperty","fixedVersion":"1.9.11"},{"ecosystem":"NuGet","name":"MessagePack.ReactiveProperty","fixedVersion":"2.1.90"},{"ecosystem":"NuGet","name":"MessagePack.UnityShims","fixedVersion":"1.9.11"},{"ecosystem":"NuGet","name":"MessagePack.UnityShims","fixedVersion":"2.1.90"},{"ecosystem":"NuGet","name":"MessagePack.Unity","fixedVersion":"1.9.11"},{"ecosystem":"NuGet","name":"MessagePack.Unity","fixedVersion":"2.1.90"}],"fix":{"url":"https://github.com/neuecc/MessagePack-CSharp/commit/56fa86219d01d0a183babbbbcb34abbdea588a02","label":"neuecc/MessagePack-CSharp@56fa862"},"references":[{"type":"ADVISORY","url":"https://github.com/neuecc/MessagePack-CSharp/security/advisories/GHSA-7q36-4xx7-xcxf"},{"type":"REPORT","url":"https://github.com/neuecc/MessagePack-CSharp/issues/810"},{"type":"FIX","url":"https://github.com/neuecc/MessagePack-CSharp/commit/56fa86219d01d0a183babbbbcb34abbdea588a02"},{"type":"FIX","url":"https://github.com/neuecc/MessagePack-CSharp/commit/f88684078698386df02204f13faeff098a61f007"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-08-27T08:40:28.601814Z"}}