{"id":"RUSTSEC-2026-0090","revision":null,"records":[{"revision":"636fb517f1ae4c86a60e77cf9638d832","observedAt":"2026-10-23T15:48:27.903+00:00","statement":{"source":"cve-program","id":"CVE-2026-34983","aliases":[],"title":"Wasmtime has a use-after-free bug after cloning `wasmtime::Linker`","description":"Wasmtime is a runtime for WebAssembly. In 43.0.0, cloning a wasmtime::Linker is unsound and can result in use-after-free bugs. This bug is not controllable by guest Wasm programs. It can only be triggered by a specific sequence of embedder API calls made by the host. Specifically, the following steps must occur to trigger the bug clone a wasmtime::Linker, drop the original linker instance, use the new, cloned linker instance, resulting in a use-after-free. 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If you are using the embedding API but are not calling `wasmtime::Linker`'s `Clone` implementation, you are not affected.\n\nSpecifically, the following steps must occur to trigger the bug:\n\n* Clone a `wasmtime::Linker`\n* Drop the original linker instance\n* Use the new, cloned linker instance, resulting in a use-after-free\n\n### Patches\n\nThis bug has been patched in Wasmtime version 43.0.1\n\n### Workarounds\n\nWasmtime embedders are highly encouraged to upgrade their `wasmtime` crate dependency.\n\nIf upgrading is not an option, or as a temporary workaround before upgrading, you can avoid this bug by not cloning `wasmtime::Linker` and instead creating a new, empty `wasmtime::Linker` and manually reregistering the host APIs from the original linker:\n\n```rust\nuse wasmtime::{Linker, Result, Store};\n\nfn clone_linker<T>(linker: &Linker<T>, store: &mut Store<T>) -> Result<Linker<T>> {\n    let mut cloned = Linker::new();\n    for (module, name, item) in linker.iter(store) {\n        cloned.define(module, name, item)?;\n    }\n    Ok(cloned)\n}\n```\n\n### References\n\nThis bug was introduced during an internal refactoring that was part of our efforts to [robustly handle allocation failure in Wasmtime](https://github.com/bytecodealliance/wasmtime/issues/12069). This refactoring introduced an string-interning pool which had an unsound `TryClone`[^try-clone] implementation.\n\n[^try-clone]: [The `TryClone` trait](https://github.com/bytecodealliance/wasmtime/blob/33e8b3d955697587b23cf39d87fbcbdb4d26b0c9/crates/core/src/alloc/try_clone.rs#L5-L17) is our version of the Rust standard library's `Clone` trait that allows for returning `OutOfMemory` errors.\n\n* The `StringPool` was introduced in https://github.com/bytecodealliance/wasmtime/pull/12536, at which time the bug in `TryClone for StringPool` was already present, although this code path was not yet used anywhere.\n* `wasmtime::Linker` was refactored to internally use `StringPool` in https://github.com/bytecodealliance/wasmtime/pull/12537, at which time the buggy code path became accessible.\n* This bug was originally reported to the Wasmtime maintainers as https://github.com/bytecodealliance/wasmtime/pull/12906","state":0,"publishedAt":"2026-04-09T20:23:44+00:00","modifiedAt":"2026-09-10T03:51:01.9502511+00:00","affected":[{"ecosystem":"crates.io","name":"wasmtime","ranges":[{"type":"SEMVER","events":[{"kind":"introduced","version":"43.0.0"},{"kind":"fixed","version":"43.0.1"}]}],"versions":["43.0.0"],"rawVersionEvidence":null}],"metrics":[{"system":"CVSS_V4","vector":"CVSS:4.0/AV:P/AC:H/AT:P/PR:H/UI:A/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N","score":null,"severity":null},{"system":"Publisher rating","vector":null,"score":null,"severity":"LOW"}],"references":["https://github.com/bytecodealliance/wasmtime/security/advisories/GHSA-hfr4-7c6c-48w2","https://nvd.nist.gov/vuln/detail/CVE-2026-34983","https://github.com/bytecodealliance/wasmtime","https://github.com/pypa/advisory-database/tree/main/vulns/wasmtime/PYSEC-2026-151.yaml","https://rustsec.org/advisories/RUSTSEC-2026-0090.html"],"sourceUrl":"https://github.com/advisories/GHSA-hfr4-7c6c-48w2","license":"GitHub Advisory Database · CC-BY-4.0","key":"osv:GHSA-hfr4-7c6c-48w2","identifiers":["GHSA-hfr4-7c6c-48w2","CVE-2026-34983","PYSEC-2026-151","RUSTSEC-2026-0090"]},"retained":false,"historicalAffected":[]},{"revision":"777c66f987a344efb9259c2d6432b98a","observedAt":"2026-10-24T13:19:54.901+00:00","statement":{"source":"osv","id":"RUSTSEC-2026-0090","aliases":["CVE-2026-34983","GHSA-hfr4-7c6c-48w2","PYSEC-2026-151"],"title":"Use-after-free bug after cloning `wasmtime::Linker`","description":"This is an entry in the RustSec database for the Wasmtime security advisory\nlocated at\nhttps://github.com/bytecodealliance/wasmtime/security/advisories/GHSA-hfr4-7c6c-48w2\nFor more information see the GitHub-hosted security advisory.","state":0,"publishedAt":"2026-04-09T12:00:00+00:00","modifiedAt":"2026-10-12T18:00:09.2431864+00:00","affected":[{"ecosystem":"crates.io","name":"wasmtime","ranges":[{"type":"SEMVER","events":[{"kind":"introduced","version":"43.0.0"},{"kind":"fixed","version":"43.0.1"}]}],"versions":[],"rawVersionEvidence":null}],"metrics":[{"system":"CVSS_V4","vector":"CVSS:4.0/AV:P/AC:H/AT:P/PR:H/UI:A/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N","score":null,"severity":null}],"references":["https://crates.io/crates/wasmtime","https://rustsec.org/advisories/RUSTSEC-2026-0090.html","https://github.com/bytecodealliance/wasmtime/issues/12069"],"sourceUrl":"https://osv.dev/vulnerability/RUSTSEC-2026-0090","license":"OSV · upstream source license applies","key":"osv:RUSTSEC-2026-0090","identifiers":["RUSTSEC-2026-0090","CVE-2026-34983","GHSA-hfr4-7c6c-48w2","PYSEC-2026-151"]},"retained":false,"historicalAffected":[]}],"coverage":[{"source":"cisa-kev:global","scope":"Complete CISA KEV catalog; all vendors. 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