# CVE-2026-119138: Wasmtime assertion failure after trap in pending calls

Source: https://junglewise.ai/threats/cve-2026-119138-wasmtime-46-0-0-before-48-0-6-and-49-0-0-before-49-0-3-contains  
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-2026-119138 · Severity: medium · CVSS 4.8 · Published 2026-10-29

Wasmtime is a WebAssembly runtime used to execute untrusted code safely in applications. A denial-of-service vulnerability allows attackers to supply misbehaving WebAssembly code that triggers a trap, leaving the execution environment in a poisoned state. When earlier pending calls are allowed to continue after this trap, the runtime crashes with an assertion failure, disrupting the application.

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-2026-119138 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-119138 being exploited in the wild.

**How severe is CVE-2026-119138?** Medium severity, with a CVSS score of 4.8, published 29 October 2026.

**Which products and versions are affected?** Bytecode Alliance Wasmtime >= 46.0.0 before 48.0.6, >= 49.0.0 before 49.0.3.

**Is there a fix for CVE-2026-119138?** Yes: fixed in 48.0.6, 49.0.3. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-119138 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-119138?** 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 48.0.6, 49.0.3

## Technical details

The vulnerability occurs in the Store state management when a trap (runtime exception) is triggered by guest code, leaving the Store in an inconsistent state. If event loop tasks are permitted to run after this poisoning and complete earlier pending calls, an assertion failure is triggered, causing a panic. The attack requires the ability to supply guest code and for the embedder to continue using the Store after an error, with network-level attack possible but requiring high complexity and low privileges.

## Affected products

- Bytecode Alliance Wasmtime >= 46.0.0 before 48.0.6, >= 49.0.0 before 49.0.3

## Timeline

- 2026-10-14: disclosed
- 2026-10-29: advisory

## References

- [https://github.com/bytecodealliance/wasmtime/security/advisories/GHSA-hmwq-g22x-qjw5](https://github.com/bytecodealliance/wasmtime/security/advisories/GHSA-hmwq-g22x-qjw5)
- [https://www.vulncheck.com/advisories/wasmtime-46.0.0-before-48.0.6-and-49.0.0-before-49.0.3-panic-after-trap](https://www.vulncheck.com/advisories/wasmtime-46.0.0-before-48.0.6-and-49.0.0-before-49.0.3-panic-after-trap)

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