CVE-2026-119135 Wasmtime 46.0.0 before 48.0.6 and 49.0.0 before 49.0.3 Panic via StreamReader Type Mismatch
- Exploited in the wild
- Not known
- Fix
- Available
What is CVE-2026-119135?
CVE-2026-119135 is a medium-severity vulnerability in bytecodealliance wasmtime, published on 29 Oct 2026.
Official 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.
Weakness: CWE-617
Which versions are affected by CVE-2026-119135?
1 open source package ship an affected version, including wasmtime.
| Package | Affected | Fixed in |
|---|---|---|
wasmtime crates.io | From 46.0.0 | 48.0.6, 49.0.3 |
How do I fix CVE-2026-119135?
Upgrade wasmtime to a fixed version for your release line: 48.0.6 or 49.0.3.
Is CVE-2026-119135 being exploited?
There is no known exploitation of CVE-2026-119135 in the wild and no public exploit code.
Sources
Also known as GHSA-63h4-6cx9-pjfj, GHSA-68fq-q9rp-8gvr, RUSTSEC-2026-0355.