# CVE-2026-119132: Wasmtime host panic via overlapping string transcode in fused adapter

Source: https://junglewise.ai/threats/cve-2026-119132-wasmtime-from-49-0-0-before-49-0-3-contains-a-denial-of-service  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-10-29. Updated: 2026-10-29  
License: CC BY 4.0 with a link back

CVE-2026-119132 · Severity: medium · CVSS 4.8 · Published 2026-10-29

Wasmtime is a WebAssembly runtime that executes untrusted code in a sandboxed environment. A flaw in versions 49.0.0 through 49.0.2 allows a malicious WebAssembly guest to crash the host by triggering a panic during string transcoding between components, resulting in a denial-of-service attack on systems running the vulnerable runtime.

Technologies: [Bytecode Alliance Wasmtime](https://junglewise.ai/threats/technologies/bytecode-alliance-wasmtime). Vendors: [Bytecode Alliance](https://junglewise.ai/threats/vendors/bytecode-alliance).

## Quick answers

**Is CVE-2026-119132 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-119132 being exploited in the wild.

**How severe is CVE-2026-119132?** Medium severity, with a CVSS score of 4.8, published 29 October 2026.

**Which products and versions are affected?** Bytecode Alliance Wasmtime 49.0.0 through 49.0.2.

**Is there a fix for CVE-2026-119132?** Yes: fixed in 49.0.3. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-119132 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-119132?** Check whether you run Bytecode Alliance Wasmtime 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

- Fixed in 49.0.3

## Technical details

The vulnerability exists in Wasmtime's fused adapter implementation, where overlapping string transcoding during same-instance component-to-component calls causes a panic instead of raising a trap. Specifically, when a string's source and destination memory locations alias each other, the refactored code path in version 49.0.0+ fails to properly detect and handle this condition, allowing a guest to reach an unsafe code path that panics the host process. This is a network-reachable denial-of-service vector requiring low privileges and passive user interaction (code execution).

## Affected products

- Bytecode Alliance Wasmtime 49.0.0 through 49.0.2

## Timeline

- 2026-10-14: disclosed
- 2026-10-29: advisory
- 2026-10-29: patched: Wasmtime 49.0.3 released

## References

- [https://github.com/bytecodealliance/wasmtime/security/advisories/GHSA-54p9-vhhq-8f7q](https://github.com/bytecodealliance/wasmtime/security/advisories/GHSA-54p9-vhhq-8f7q)
- [https://www.vulncheck.com/advisories/wasmtime-49.0.0-before-49.0.3-host-panic-via-overlapping-string-transcode-in-fused-adapter](https://www.vulncheck.com/advisories/wasmtime-49.0.0-before-49.0.3-host-panic-via-overlapping-string-transcode-in-fused-adapter)

## Related threats

- [Wasmtime wasi-http response splitting via unvalidated headers](https://junglewise.ai/threats/cve-2026-121439-wasmtime-46-0-0-before-48-0-7-and-49-0-0-before-49-0-4-contains)
- [Wasmtime denial of service in component model stream operations](https://junglewise.ai/threats/cve-2026-119143-wasmtime-46-0-0-before-48-0-6-and-49-0-0-before-49-0-3-contains)
- [Wasmtime host panic in call_async Future drop](https://junglewise.ai/threats/cve-2026-119142-wasmtime-46-0-0-before-48-0-6-and-49-0-0-before-49-0-3-contains)
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- [Wasmtime denial of service via thread.yield in component start](https://junglewise.ai/threats/cve-2026-119140-wasmtime-46-0-0-before-48-0-6-and-49-0-0-before-49-0-3-contains)