Improper MLS Welcome roster validation in Discord libdave allows unauthorized group membership

{
                    "vendor": "Discord",
                    "product": "libdave",
                    "modules": [
                        "C++ library"
                    ],
                    "collectionURL": "https://github.com",
                    "packageName": "discord/libdave",
                    "repo": "https://github.com/discord/libdave",
                    "programFiles": [
                        "cpp/src/mls/session.cpp"
                    ],
                    "programRoutines": [
                        {
                            "name": "discord::dave::mls::Session::VerifyWelcomeState"
                        }
                    ],
                    "defaultStatus": "unaffected",
                    "versions": [
                        {
                            "version": "1.1.0",
                            "status": "affected",
                            "lessThan": "1.2.0",
                            "versionType": "semver"
                        },
                        {
                            "version": "7b15f1fc16f159da0478aa6be909e38f1e957833",
                            "status": "affected",
                            "lessThan": "9686fbaea864aa19f0675e486672b6a77811b6a1",
                            "versionType": "git"
                        }
                    ]
                }