{"id":"CVE-2021-39219","details":"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`.","aliases":["CVE-2021-39216","CVE-2021-39218","GHSA-4873-36h9-wv49","GHSA-q879-9g95-56mx","GHSA-v4cp-h94r-m7xf","PYSEC-2021-320","PYSEC-2021-321","PYSEC-2021-322","RUSTSEC-2021-0110"],"modified":"2026-04-10T04:37:03.919502Z","published":"2021-09-17T20:15:07.763Z","related":["GHSA-q879-9g95-56mx"],"references":[{"type":"WEB","url":"https://crates.io/crates/wasmtime"},{"type":"WEB","url":"https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/WAVBRYDDUIY2ZR3K3FO4BVYJKIMJ5TP7/"},{"type":"WEB","url":"https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/Z2Z33FTXFQ6EOINVEQIP4DFBG53G5XIY/"},{"type":"ADVISORY","url":"https://github.com/bytecodealliance/wasmtime/security/advisories/GHSA-q879-9g95-56mx"},{"type":"FIX","url":"https://github.com/bytecodealliance/wasmtime/commit/b39f087414f27ae40c44449ed5d1154e03449bff"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/bytecodealliance/wasmtime","events":[{"introduced":"0"},{"fixed":"572fbc8c54b5a9519154c57e28b86cfaaba57bbb"},{"introduced":"0"},{"last_affected":"509af9e5fb6c43f95428c3b297882bbf746faa5e"},{"fixed":"b39f087414f27ae40c44449ed5d1154e03449bff"}],"database_specific":{"versions":[{"introduced":"0"},{"fixed":"0.30.0"},{"introduced":"0"},{"last_affected":"35"}]}}],"versions":["cranelift-v0.60.0","cranelift-v0.61.0","cranelift-v0.69.0","v0.12.0","v0.16.0","v0.17.0","v0.18.0","v0.19.0","v0.20.0","v0.21.0","v0.22.0","v0.23.0","v0.24.0","v0.25.0","v0.26.0","v0.27.0","v0.28.0","v0.29.0","v0.30.0","v0.31.0","v0.32.0","v0.33.0","v0.34.0","v0.35.0","v35.0.0"],"database_specific":{"unresolved_ranges":[{"events":[{"introduced":"0"},{"last_affected":"34"}]}],"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2021-39219.json"}}],"schema_version":"1.7.5","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:H/A:H"}]}