CVE-2021-39216

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Summary

CVECVE-2021-39216
StatePUBLIC
Assigner[email protected]
Source PriorityCVE Program / NVD first with legacy fallback
Published2021-09-17 20:15:00 UTC
Updated2023-11-07 03:37:00 UTC
DescriptionWasmtime is an open source runtime for WebAssembly & WASI. In Wasmtime from version 0.19.0 and before version 0.30.0 there was a use-after-free bug when passing `externref`s from the host to guest Wasm content. To trigger the bug, you have to explicitly pass multiple `externref`s from the host to a Wasm instance at the same time, either by passing multiple `externref`s as arguments from host code to a Wasm function, or returning multiple `externref`s to Wasm from a multi-value return function defined in the host. If you do not have host code that matches one of these shapes, then you are not impacted. If Wasmtime's `VMExternRefActivationsTable` became filled to capacity after passing the first `externref` in, then passing in the second `externref` could trigger a garbage collection. However the first `externref` is not rooted until we pass control to Wasm, and therefore could be reclaimed by the collector if nothing else was holding a reference to it or otherwise keeping it alive. Then, when control was passed to Wasm after the garbage collection, Wasm could use the first `externref`, which at this point has already been freed. We have reason to believe that the effective impact of this bug is relatively small because usage of `externref` is currently quite rare. The bug has been fixed, and users should upgrade to Wasmtime 0.30.0. If you cannot upgrade Wasmtime yet, you can avoid the bug by disabling reference types support in Wasmtime by passing `false` to `wasmtime::Config::wasm_reference_types`.

Risk And Classification

Problem Types: CWE-416

NVD Known Affected Configurations (CPE 2.3)

TypeVendorProductVersionUpdateEditionLanguage
Application Bytecodealliance Wasmtime All All All All
Operating System Fedoraproject Fedora 34 All All All
Operating System Fedoraproject Fedora 35 All All All

References

ReferenceSourceLinkTags
crates.io/crates/wasmtime MISC crates.io
Use after free passing `externref`s to Wasm in Wasmtime · Advisory · bytecodealliance/wasmtime · GitHub CONFIRM github.com
[SECURITY] Fedora 34 Update: rust-wasmtime-fiber-0.30.0-1.fc34 - package-announce - Fedora Mailing-Lists lists.fedoraproject.org
[SECURITY] Fedora 34 Update: rust-wasmtime-fiber-0.30.0-1.fc34 - package-announce - Fedora Mailing-Lists FEDORA lists.fedoraproject.org
[SECURITY] Fedora 35 Update: rust-cranelift-frontend-0.77.0-1.fc35 - package-announce - Fedora Mailing-Lists FEDORA lists.fedoraproject.org
[SECURITY] Fedora 35 Update: rust-cranelift-frontend-0.77.0-1.fc35 - package-announce - Fedora Mailing-Lists lists.fedoraproject.org
Merge pull request from GHSA-v4cp-h94r-m7xf · bytecodealliance/wasmtime@1019987 · GitHub MISC github.com
CVE Program record CVE.ORG www.cve.org canonical
NVD vulnerability detail NVD nvd.nist.gov canonical, analysis

Legacy QID Mappings

  • 281958 Fedora Security Update for rust (FEDORA-2021-1805eacb48)
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