{
    "CVE_data_meta": {
        "ASSIGNER": "security-advisories@github.com",
        "ID": "CVE-2021-39219",
        "STATE": "PUBLIC",
        "TITLE": "Wrong type for `Linker`-define functions when used across two `Engine`s"
    },
    "affects": {
        "vendor": {
            "vendor_data": [
                {
                    "product": {
                        "product_data": [
                            {
                                "product_name": "wasmtime",
                                "version": {
                                    "version_data": [
                                        {
                                            "version_value": "<= 0.29.0"
                                        }
                                    ]
                                }
                            }
                        ]
                    },
                    "vendor_name": "bytecodealliance"
                }
            ]
        }
    },
    "data_format": "MITRE",
    "data_type": "CVE",
    "data_version": "4.0",
    "description": {
        "description_data": [
            {
                "lang": "eng",
                "value": "Wasmtime is an open source runtime for WebAssembly & WASI. Wasmtime before version 0.30.0 is affected by a type confusion vulnerability. As a Rust library the `wasmtime` crate clearly marks which functions are safe and which are `unsafe`, guaranteeing that if consumers never use `unsafe` then it should not be possible to have memory unsafety issues in their embeddings of Wasmtime. An issue was discovered in the safe API of `Linker::func_*` APIs. These APIs were previously not sound when one `Engine` was used to create the `Linker` and then a different `Engine` was used to create a `Store` and then the `Linker` was used to instantiate a module into that `Store`. Cross-`Engine` usage of functions is not supported in Wasmtime and this can result in type confusion of function pointers, resulting in being able to safely call a function with the wrong type. Triggering this bug requires using at least two `Engine` values in an embedding and then additionally using two different values with a `Linker` (one at the creation time of the `Linker` and another when instantiating a module with the `Linker`). It's expected that usage of more-than-one `Engine` in an embedding is relatively rare since an `Engine` is intended to be a globally shared resource, so the expectation is that the impact of this issue is relatively small. The fix implemented is to change this behavior to `panic!()` in Rust instead of silently allowing it. Using different `Engine` instances with a `Linker` is a programmer bug that `wasmtime` catches at runtime. This bug has been patched and users should upgrade to Wasmtime version 0.30.0. If you cannot upgrade Wasmtime and are using more than one `Engine` in your embedding it's recommended to instead use only one `Engine` for the entire program if possible. An `Engine` is designed to be a globally shared resource that is suitable to have only one for the lifetime of an entire process. If using multiple `Engine`s is required then code should be audited to ensure that `Linker` is only used with one `Engine`."
            }
        ]
    },
    "impact": {
        "cvss": {
            "attackComplexity": "HIGH",
            "attackVector": "LOCAL",
            "availabilityImpact": "HIGH",
            "baseScore": 6.3,
            "baseSeverity": "MEDIUM",
            "confidentialityImpact": "NONE",
            "integrityImpact": "HIGH",
            "privilegesRequired": "NONE",
            "scope": "UNCHANGED",
            "userInteraction": "REQUIRED",
            "vectorString": "CVSS:3.1/AV:L/AC:H/PR:N/UI:R/S:U/C:N/I:H/A:H",
            "version": "3.1"
        }
    },
    "problemtype": {
        "problemtype_data": [
            {
                "description": [
                    {
                        "lang": "eng",
                        "value": "CWE-843: Access of Resource Using Incompatible Type ('Type Confusion')"
                    }
                ]
            }
        ]
    },
    "references": {
        "reference_data": [
            {
                "name": "https://crates.io/crates/wasmtime",
                "refsource": "MISC",
                "url": "https://crates.io/crates/wasmtime"
            },
            {
                "name": "https://github.com/bytecodealliance/wasmtime/security/advisories/GHSA-q879-9g95-56mx",
                "refsource": "CONFIRM",
                "url": "https://github.com/bytecodealliance/wasmtime/security/advisories/GHSA-q879-9g95-56mx"
            },
            {
                "name": "https://github.com/bytecodealliance/wasmtime/commit/b39f087414f27ae40c44449ed5d1154e03449bff",
                "refsource": "MISC",
                "url": "https://github.com/bytecodealliance/wasmtime/commit/b39f087414f27ae40c44449ed5d1154e03449bff"
            },
            {
                "refsource": "FEDORA",
                "name": "FEDORA-2021-68713440cb",
                "url": "https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/Z2Z33FTXFQ6EOINVEQIP4DFBG53G5XIY/"
            },
            {
                "refsource": "FEDORA",
                "name": "FEDORA-2021-1805eacb48",
                "url": "https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/WAVBRYDDUIY2ZR3K3FO4BVYJKIMJ5TP7/"
            }
        ]
    },
    "source": {
        "advisory": "GHSA-q879-9g95-56mx",
        "discovery": "UNKNOWN"
    }
}