# CVE-2026-119134: Wasmtime component-model resource handle unbounded memory growth

Source: https://junglewise.ai/threats/cve-2026-119134-wasmtime-before-36-0-18-37-0-0-before-48-0-6-and-49-0-0-before  
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-2026-119134 · Severity: medium · CVSS 6.2 · Published 2026-10-29

Wasmtime is a runtime for WebAssembly, a technology that allows untrusted code to execute in a sandboxed environment. A vulnerability in how Wasmtime manages memory allocation for component-model resource handles allows a malicious WebAssembly guest to consume unbounded amounts of host memory, causing a denial of service. This could crash applications relying on Wasmtime or make them unresponsive.

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-2026-119134 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-119134 being exploited in the wild.

**How severe is CVE-2026-119134?** Medium severity, with a CVSS score of 6.2, published 29 October 2026.

**Which products and versions are affected?** Bytecode Alliance Wasmtime before 36.0.18, 37.0.0 before 48.0.6, 49.0.0 before 49.0.3.

**Is there a fix for CVE-2026-119134?** Yes: fixed in 36.0.18, 48.0.6, 49.0.3. Until then: Set a store-wide limit on component-model handles using the Store::set_max_component_handles(n) embedder API or the -S max-component-handles=N CLI flag to restrict memory growth; the default limit is 100,000 live handles per store (~2.4 MB). Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-119134 attacked?** It is attacked with local access.

**Am I affected by CVE-2026-119134?** 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 36.0.18, 48.0.6, 49.0.3

Set a store-wide limit on component-model handles using the Store::set_max_component_handles(n) embedder API or the -S max-component-handles=N CLI flag to restrict memory growth; the default limit is 100,000 live handles per store (~2.4 MB).

## Technical details

The vulnerability exists in Wasmtime's component-model implementation, where resource handle table allocations are capped only per component instance and are not charged to ResourceLimiter or StoreLimits. A malicious guest can call resource.new repeatedly and instantiate sub-components to bypass the per-instance cap, causing unbounded memory growth on the host. The attack requires local/guest code execution but no special privileges or user interaction.

## Affected products

- Bytecode Alliance Wasmtime before 36.0.18, 37.0.0 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-q554-3cjc-rx7p](https://github.com/bytecodealliance/wasmtime/security/advisories/GHSA-q554-3cjc-rx7p)
- [https://www.vulncheck.com/advisories/wasmtime-before-36.0.18-37.0.0-before-48.0.6-and-49.0.0-before-49.0.3-unbounded-memory-growth-via-component-model-resource-handles](https://www.vulncheck.com/advisories/wasmtime-before-36.0.18-37.0.0-before-48.0.6-and-49.0.0-before-49.0.3-unbounded-memory-growth-via-component-model-resource-handles)

## Related threats

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- [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)