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OpenAdvisories
Medium · 4.8 CVE-2026-119135 EUVD-2026-113202GHSA-63h4-6cx9-pjfjGHSA-68fq-q9rp-8gvrRUSTSEC-2026-0355

Wasmtime 46.0.0 before 48.0.6 and 49.0.0 before 49.0.3 Panic via StreamReader Type Mismatch

Published Oct 29, 2026 · Updated Nov 4, 2026 · Assigned by VulnCheck

Description

Wasmtime 46.0.0 before 48.0.6 and 49.0.0 before 49.0.3 panics when the host reads a component model stream as a different Rust item type than it was created with, because the host-to-host read path asserts matching TypeIds instead of returning an error. Guest code can return a host-created StreamReader<U> that the embedder reads as StreamReader<T>, where both types map to the same component model type, crashing the embedding process.

Affected products

VendorProductAffectedFixed
bytecodealliance wasmtime 46.0.0 – < 48.0.6, 49.0.0 – < 49.0.3 48.0.6

Fixed in Linux distributions

Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.

ReleasePackageFixed inAdvisory
Ubuntu 26.10 rust-wasmtime No fix yet —
Ubuntu 26.04 LTS rust-wasmtime No fix yet —
Ubuntu 24.04 LTS rust-wasmtime No fix yet —

Affected packages

EcosystemPackageAffectedFixedRecord
crates.io wasmtime >= 46.0.0, < 48.0.6 · >= 49.0.0, < 49.0.3 48.0.6, 49.0.3 RUSTSEC-2026-0355

References