# CVE-2026-115892: Wasmtime: Panic lowering a host-created component model stream into a guest that expects a different payload type


- **Severity:** Medium 5.7 (`CVSS:4.0/AV:N/AC:H/AT:P/PR:H/UI:P/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Fix available:** Yes
- **Published:** 23 Oct 2026
- **Updated:** 29 Oct 2026
- **Also known as:** GHSA-9pvw-hwfg-92h5, RUSTSEC-2026-0378, UBUNTU-CVE-2026-115892

## What is CVE-2026-115892?

CVE-2026-115892 is a medium-severity vulnerability in bytecodealliance wasmtime, published on 23 Oct 2026. 

### Official description

Wasmtime is a runtime for WebAssembly. From 46.0.0 until 48.0.7 and 49.0.4, lowering a host-created component-model stream or future into a guest can omit a required payload-type check after the value passes through guest code and returns through StreamAny, FutureAny, Val::Stream, Val::Future, or an equivalent typed reader. A malicious guest that controls exported function types or returned values can cause the host to pass the type-erased value to a guest expecting a different payload type, which panics the Wasmtime host. This issue is fixed in versions 48.0.7 and 49.0.4.

Weakness: CWE-843 (Access of Resource Using Incompatible Type), CWE-248 (Uncaught Exception)

## Which versions are affected by CVE-2026-115892?

5 open source packages ship an affected version, including wasmtime.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `wasmtime` | crates.io | From 46.0.0 | 48.0.7, 49.0.4 |
| `wasmtime` | crates.io | From 46.0.0 | 48.0.7 |
| `wasmtime` | crates.io | From 46.0.0 | 48.0.7 |
| `wasmtime` | crates.io | From 49.0.0 | 49.0.4 |
| `wasmtime` | crates.io | From 49.0.0 | 49.0.4 |

## How do I fix CVE-2026-115892?

Upgrade wasmtime to a fixed version for your release line: 48.0.7 or 49.0.4.

## Is CVE-2026-115892 being exploited?

There is no known exploitation of CVE-2026-115892 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-115892 and fix it if it is affected.

What it is: CVE-2026-115892 is a medium-severity vulnerability in bytecodealliance wasmtime, published on 23 Oct 2026. 
Exploitation: There is no known exploitation of CVE-2026-115892 in the wild and no public exploit code.

Affected packages and fixed versions:
- wasmtime (crates.io): affected from 46.0.0; fixed in 48.0.7, 49.0.4
- wasmtime (crates.io): affected from 46.0.0; fixed in 48.0.7
- wasmtime (crates.io): affected from 46.0.0; fixed in 48.0.7
- wasmtime (crates.io): affected from 49.0.0; fixed in 49.0.4
- wasmtime (crates.io): affected from 49.0.0; fixed in 49.0.4

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-115892/ (Markdown: https://insights.sbomify.com/CVE-2026-115892/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-115892
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-115892
- OSV: https://osv.dev/vulnerability/CVE-2026-115892

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-115892/
Summaries are generated and may contain mistakes; the official description above is the record.