Is This vulnerability exploited in the wild?

No. Junglewise Threat Intelligence has no report of This vulnerability being exploited in the wild.

How severe is This vulnerability?

Medium severity, with a CVSS score of 4, published 14 October 2026.

Which products and versions are affected?

Bytecode Alliance Wasmtime 46.0.0 through 48.0.5, 49.0.0 through 49.0.2; wasmtime (crates.io) SEMVER:introduced=46.0.0,fixed=48.0.6,introduced=49.0.0,fixed=49.0.3.

Is there a fix for This vulnerability?

Yes. wasmtime (crates.io): upgrade to 49.0.3 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

How is This vulnerability attacked?

It is attacked over the network.

Check whether you run Bytecode Alliance Wasmtime or wasmtime (crates.io) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

Wasmtime host panic in call_async cancellation

Severity: medium · CVSS 4 · Published 2026-10-14

Wasmtime is a WebAssembly runtime used to execute untrusted code. Under specific conditions when an asynchronous component call is cancelled, the host process can panic, causing a denial of service. An attacker with low privileges and the ability to trigger component cancellation could crash the application.

Technologies: Bytecode Alliance Wasmtime, wasmtime (crates.io). Vendors: Bytecode Alliance, crates.io.

Quick answers

Is This vulnerability exploited in the wild?: No. Junglewise Threat Intelligence has no report of This vulnerability being exploited in the wild.
How severe is This vulnerability?: Medium severity, with a CVSS score of 4, published 14 October 2026.
Which products and versions are affected?: Bytecode Alliance Wasmtime 46.0.0 through 48.0.5, 49.0.0 through 49.0.2; wasmtime (crates.io) SEMVER:introduced=46.0.0,fixed=48.0.6,introduced=49.0.0,fixed=49.0.3.
Is there a fix for This vulnerability?: Yes. wasmtime (crates.io): upgrade to 49.0.3 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is This vulnerability attacked?: It is attacked over the network.
Am I affected?: Check whether you run Bytecode Alliance Wasmtime or wasmtime (crates.io) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

How to fix

wasmtime (crates.io): upgrade to 49.0.3 or later
```
cargo update -p wasmtime
```

Technical details

A panic occurs in Wasmtime's `call_async` component function when cancellation is triggered under certain conditions. The vulnerability requires network access, low privileges, passive user interaction, and specific attack prerequisites. Successful exploitation results in denial of service to the host system through an unhandled panic.

Affected products

Bytecode Alliance Wasmtime 46.0.0 through 48.0.5, 49.0.0 through 49.0.2

Identifiers

GHSA-3r89-v5mq-j5xf
RUSTSEC-2026-0354

Timeline

2026-10-14: disclosed
2026-10-14: advisory

References

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